There is something slightly irritating about the prime minister's insistence that it is down to us consumers to cut our food waste. Less than half of the food thrown away each year comes from households. To suggest that the average householder is to blame for our colossal national wastage is to ignore the way that the food industry has been allowed to develop in this country, from the relentless rise of the supermarket to the flourishing of the fast-food outlet, the decline in farming and the death of the local shop. All of these affect why we buy the wrong things, and why we buy so much of what we do not need.

Add to this changes in family structure, transformations in the shape of our towns and cities, moves to online shopping and shifts in working patterns and it's easy to see how we have become untethered from traditional production and consumption of food; today we tend to shop once a week, more often than not driving to an out-of-town supermarket rather than shopping locally, where we buy food increasingly prepared in a way that makes it go off faster, by manufacturers so scared of litigation that they stamp their products with sell-by and best-before dates.

Still, it would be churlish not to do our bit - so here we present 20 tips to waste not want not:

1. Avoid the supermarket

"Supermarkets are very expensive places to shop," says Joanna Blythman, author of Shopped: The Shocking Power of British Supermarkets. "The idea of the one-stop shop encourages you to buy more than you need." If you do have to go to a supermarket, make a list of what you need beforehand, and stick to it rigorously - but do check that these are groceries you genuinely need, and not items you have just got into the habit of buying: "There's the Stepford Wives aspect of supermarket shopping, where you start buying the same thing every time," says Blythman, "the same yoghurt regardless of whether you've run out of the last tub. But I just say don't shop in supermarkets. They are a rip-off."

2. Ignore two-for one offers

More often than not, supermarket two-for-ones exist because the items in question are nearing their use-by date, or to give shoppers what Blythman refers to as "the halo effect" - the feeling that they are in a place of endless bargains. But stop and think: are you really going to eat those 12 iced buns before they go stale? Are most of the cherries in those punnets even edible? Just how much custard do you require? "Two-for-ones are just encouraging overspending," says Blythman. "They're getting you to buy more than you need." Rose Prince, author of the Savvy Shopper, is also sceptical: "All this means is the supermarket has doubled the price for a given period and then halved the doubled price. Amazing, isn't it?" However, such offers can occasionally prove useful, if you are able to think laterally: "They are great value, but only provided you know how you can use the extra food," says Richard Swannell, director of retail programmes at Wrap, the organisation behind the website lovefoodhatewaste.com. "It's just being clear in your mind that you are going to use one and freeze the other."

3. Shop daily for perishables

By shopping daily for what you need, you are less likely to buy mounds of vegetables, meat and fish that will then sit in the fridge going off. Plus you will re-establish a connection with those who produce the food you eat. "The problem is that the distance between the people eating and the people supplying the food is getting longer and longer," says Moritz Steiger, co-author, with Effie Fotaki, of the Independent London Store Guide. Steiger points to the establishment of smaller, neighbourhood supermarkets such as Tesco Metro and Sainsbury's Local as evidence that we still have a desire for corner shops, but these smaller supermarket branches do not necessarily supply the best quality of food, nor do they offer the best deal for the supplier or the customer. Blythman agrees: "Supermarkets generally charge more than the independent greengrocer for fresh fruit and vegetables, especially seasonal produce." As does Prince: "My own researches show that you'll save a minimum of 35% - and usually a lot more."

4. Bulk-buy non-perishables

Bulk-buying storecupboard staples, such as rice, pasta and lentils, along with tinned and bottled items, online is cheaper than visiting the supermarket - not least because it considerably reduces the likelihood of being enticed into buying three punnets of strawberries and a tub of sprinkly cupcakes as you stroll the aisles. "In our house we bulk-buy rice in seven kilo bags," says Swannell. "It saves on packaging and money." Various websites offer a good range of store cupboard essentials, including nifeislife.com, which offers a variety of Italian foodstuffs across the UK, and gfd.org.uk for organic health foods and wholefoods in bulk. Blythman, though, suggests that rather than shopping online you can "just visit your local wholefood shop".

5. Be storage savvy

There are tonnes of household tips for storing foods to increase their longevity (many of them appear on the lovefoodhatewaste.com site) including topping and tailing carrots as soon as you buy them to prolong their life, keeping apples in the fridge so they last days longer than in the fruit bowl, and ensuring your olive oil is kept somewhere cool and dry to prevent the breakdown of the fatty acids. Also, invest in an EGG - "ethylene gas guardian" (4theegg.com): many fruits and vegetables give off ethylene gas as they ripen and the refrigerator traps this gas, which results in the early rotting of your produce. The EGG keeps the ethylene levels in your fridge low, meaning your vegetables last longer.

6. Meal-plan for the week

If, at the beginning of the week, you work out precisely what you wish to cook over the next seven days (some of which may incorporate leftovers), you can then shop with a degree of rigour, are less likely to be distracted by appetising products on the supermarket shelves, and even less likely to end up with a heap of unused foodstuffs at the end of the week. This approach also eliminates the common feeling of returning from the supermarket laden with shopping bags but without a clue what to actually cook for dinner. "In the past," notes Blythman, "people more or less had the same thing on particular nights of the week - leftover roast on a Monday, fish on a Friday ... " and while there is no need for your menu to become quite so predictable, a degree of planning ahead saves time, money and waste and will prevent you from falling back on ready meals.

7. Cook

While many of us have become rather adept at following recipes, we have, somewhere along the way, lost the ability to actually cook - a tangibly different skill which allows you to know just what to do with all the celery you didn't use in last night's risotto, for instance, or that quarter can of coconut milk that wasn't needed in the pumpkin curry. These aren't strictly leftovers but recipe byproducts, and the accomplished cook will be able to incorporate them into subsequent meals without a great deal of fuss or research. The idea is that you don't ever buy recipe ingredients without simultaneously considering where in your culinary week the remainders - that half a courgette, that zested lemon, that quarter block of feta - will find a home. So, whereas recipes can be seen as singular events, cookery is more of an ongoing project. "We didn't used to buy chicken pieces," says Blythman. "We bought a chicken. We had it hot once, and then we scraped the bits off it for sandwiches, and then we boiled the carcass and the gizzard and used the stock to make soup or risotto. Domestic economy was always a rolling programme, you used what you had as the base, added a few extra fresh bits. It's a question of momentum." G2 chef Allegra McEvedy agrees: "There are three main areas of waste: the first is ingredients that are past their best; the second is bits surplus to a specific recipe [as in 'take a third of a courgette and one stalk of celery') and the last being what is usually understood by the term 'leftovers'. For the first, there are two ways forward: buy less and don't be so quick to toss out. Summer fruit that's lost its shape and has squidgy bits can so easily and happily become jam. Super-soft avos will live again as guacamole for the night, and shrivelled tomatoes often have better flavour than taut-skinned ones, and make a stunning tomato soup. The truth is that almost anything in the kitchen has the ability to be born-again as soup or maybe a slow one-pot braise with some spices and a couple of tins - one of tomatoes, the other of some multi-faceted pulse, such as chickpeas."

8. Buy quality not quantity

"If you buy cheap supermarket bread you have no compunction about throwing it away," argues Steiger. "If you buy quality bread you're more likely to use every last bit of it." This goes for most food items, from the fancy yoghurt you're more likely to eat before the use-by date arrives, to the gourmet biscuits you probably don't want to leave to go soggy (or gobble all in one expensive sitting).

9. Freecyle/become a 'freegan'

The freecycle.org website should point you in the direction of your nearest group of freecyclers, a "grassroots and entirely non-profit movement of people who are giving (and getting) stuff for free in their own towns". That stuff often includes perfectly usable food. Freegans take it one step further, scavenging for food from supermarket dustbins that may be about to reach or is just past its sell-by date but is invariably still edible, or whose packaging may be damaged. Supermarkets, of course, detest them because they are proof that large food retailers throw out tonne after tonne of food that could still be safely consumed; as a result, many now stash their waste bins behind barbed wire fences.

10. Reacquaint yourself with your freezer

The freezer compartment is not just for storing ice cubes, a half-eaten tub of Häagen-Dazs and several inches of encrusted ice, but also to keep leftovers for future meals. Though it's not recommended to freeze salad leaves or crunchy vegetables, it's the perfect place for portions of rice, sprinklings of herbs, pre-sliced bagels that you can pop straight into the toaster. You can even freeze cheese and eggs (so long as you separate the whites and the yolks). It's also worth noting that freezers are more efficient when full, so you'll be saving the pennies there, too. Goodhousekeeping.com has plenty of basic tips for the novice freezer.

11. Don't be afraid of an empty fridge

"I think that goes back to the rise of the big American fridge," notes Blythman. "It's an aspirational thing." You do not, therefore, need to buy acres of food each week to keep it chock-full.

12. Grow your own herbs and salad

Packets of herbs and bagged salad are among the products most likely to go off in the fridge, so if you have a garden, balcony or windowbox, use that space to grow your own. These plants grow quickly and easily and, of course, save on food miles.

13. Buy vegetables whole

A lettuce bought whole and kept in your fridge will not go off in the same way as a pre-prepared salad will, because as soon as fruit or vegetables are processed in any way - even just picked, handled and washed - they begin to decompose. Likewise, it's best not to buy carrots that have been washed, then packaged in plastic and refrigerated, as they will rot sooner than the still-soily variety stored somewhere cool and dark.

14. Know how much a portion is so you don't overcook

Never forget the simple fact that with dwindling rice and wheat crops, the more you waste, the more expensive it will become. So the easy rule is to weigh before you cook: an average portion of rice for an adult is 50g (or a quarter of a mug); for pasta, it is 100g.

15. Bulk-cook meals

Blythman advocates cooking twice as much as you need of one dish and freezing the extra portions, or you can set aside time to stock up your freezer for the coming week. "Buy a box of over-ripe tomatoes from your local street market - they virtually give them away," suggests Prince. "Make a tomato sauce and you have the base for curries, bolognese or just a plain sauce for pasta or to top a pizza. Store both stock and sauce in discarded plastic milk cartons. They freeze beautifully and when frozen you just cut the carton open and heat."

16. Learn how to use leftovers

The lovefoodhatewaste.com site has a huge array of recipes contributed by celebrity chefs, nutritionists and members of the public, including a large number dubbed "rescue recipes" - in other words, how to put that bit of leftover chicken or half courgette to delicious use. There are also websites out there (leftoverchef.com and kitchen-scraps.com, to name but two) that, one you've typed in the primary and secondary ingredients you have spare, will go away and search their databases for recipes to use them up. Bit of fish left over, and some broccoli? Try, for example, Chinese steamed fish. And a couple of books may help: Second Time Around: Ideas and Recipes for Leftovers by Pamela Le Bailly, and The Use It Up Cookbook: Creative Recipes for the Frugal Cook, by Catherine Kitcho.

17. Look to previous generations

We have, as Guardian foodie Matthew Fort puts it, a great deal more food experience than previous generations, but considerably less food knowledge. We are familiar with the taste of foods from around the world, but we've forgotten how to make the most of what we've got already. During the second world war and well into the 1950s and even 1960s, food was precious: a week's meals were planned down to the last carrot, and we used every scrap of food in our larders (few had fridges), cooking dishes such as shepherd's pie and bread-and-butter pudding precisely to use up leftover scraps. These days, we're more likely to buy them ready made from the supermarket. "People just pick what they fancy off the shelves and end up throwing half of it away because they don't know what to do with it," says Sheila Tremaine, 81. "We never threw anything away, because if you didn't use everything up you had nothing to eat. People just seem to have lost that skill." The WI was founded to help women make the most of the food they had, and has some excellent tips and recipes. Try reading that doyenne of wartime cookery writers, Marguerite Patten: We'll Eat Again, a Collection of Recipes from the War Years, and Post-War Kitchen, Nostalgic Facts and Food from 1945-54 may provide inspiration.

18. Take sell-by dates with a pinch of salt

As a general rule, only "use by" is worth taking seriously; "sell-by" and "display-until" dates are merely stock-control devices for food retailers, and "best before" is simply the producer's estimate of when the food will stop tasting good, which is fairly subjective anyway. Rather than slavishly observing these date labels, we'd be far better off understanding the kinds of foods that could actually be harmful if they go off, such as ready meals (including sandwiches), soft cheeses, pates and cooked, processed meats and seafood. Eggs with a Lion Quality stamp can be kept for weeks in the fridge; chicken, raw meats and fish will all look and smell unpleasant long before they're actively unsafe (as long as you cook it thoroughly, chicken, for example, is good for at least a week past its sell-by date). Apples last for months; potatoes are fine as long as you chop the green shoots off before cooking; tins and jars will last decades if not centuries; hard cheese is indestructible; and dry foods will last for years too. "Ignore sell-by dates," insists Swannell. "They're not relevant. And best before is just what it says on the tin; it doesn't mean the food is toxic the day after that date."

19. Rediscover packed lunches

Leftovers can easily be recycled as packed lunches for children and adults alike - not only is this more frugal, in these credit-crunching times, than a daily trip to the gourmet sandwich shop, it also cuts back on domestic waste. Try rethinking leftovers as fillings for wraps or pitta bread pockets, making leftover vegetables into sushi rolls and bruised fruit as fools or compotes.

20. Equip yourself

Introduce yourself to the stockpot, the freezer bag, and the salad spinner. "Make your own bread," says Prince. "It's quick, easy and so much better tasting than shop-bought. It's also much cheaper. Make your own ice cream, it's a doddle. Invest in a mincing machine as an attachment to a food processor, and turn the leftover roast lamb into a base for shepherd's pie. While you're at it, invest in a sausage stuffer and ask your butcher for some sausage skins when you buy the pork."

· Additional research by Andrew Murray

'Frozen food is a wonderful thing'

Readers share advice

I grow my own vegetables. Other than that I buy food on a just-in-time basis. Not only is there no waste but I don't have cupboards or a fridge full of food going off . I never buy food until I have eaten what I have. Rice, pasta and orange juice is all I will buy in bulk because it can last for many months.

TheGoodLife

Last Christmas Eve our local Lidl placed all unsold perishable foods on a large shelf on the "Out" side of the checkouts, for people to take home for free. We ate off that bonanza for about a week. Thank you Lidl! Why can't all supermarkets do this, and more often (once a week would be nice ...)?

justlookaround

The value of food wasted per household in the UK could provide the protein for an extended three/four generation family for a week. These are not UN or NGO stats ... this is me looking at our pantry here in Mexico. Send me your money and I'll buy and distribute the beans ... thought not.

biba100mejico

I usually ignore "best before" on tins. I've eaten from tins that are 3 or 4 years old.

saintleethenaked

When I buy a loaf of bread, and don't think I'll eat it all before it goes stale, I put half in the freezer - you can make toast from frozen bread directly . As for leftover veg, I tend to make soup . Made in advance, it's the perfect quick, light supper for when I get in from work.

Ephiny

Most food will last much longer than its date. Yoghurt is a good one. I'll eat it maybe 2 or 3 weeks past date and it's fine.

Nyah

Frozen food is the most wonderful thing in the world. The only things I keep in my fridge are opened jars of food or sauce and dairy products and it has made such a difference to the amount of fresh food I used to waste.

jglitter

Use-by dates are far too conservative. Use the smell test. If it smells and looks all right and you cook it well, it's fine (obviously not for seafood!)

Emma100

Buy fresh ingredients, cook from scratch and only use what you need. Don't be afraid of eating leftovers . Be open-minded about combinations of food (I'm not talking about sardines and lime jelly ...). Freeze leftovers into single portions, for defrosting and reheating later.

CleoSelene

· What will you do in the great war on rotting ready meals and mouldy mangetout? Have your say on our open thread