I love fashion. I love going to catwalk shows. I love getting dressed up. I love the illicit thrill of some frippery I can’t really afford, accompanied by the rustle of tissue paper in a crisp shopping bag – a sound bested only by a champagne cork popping. And that’s not even the half of it. More than anything, I love the thrill of the high street chase. I love stopping a woman on the street to ask where her dress is from, and hunting it down and ordering it from my phone at the bus stop. I have been known to go weak at the knees over new suede boots and I will never, ever have enough earrings.

But you know what else I love? Living in a climate that doesn’t fry me alive. Oceans with fish and icebergs in them rather than plastic. Mars is a long way – and besides, Elon Musk? No thanks. Which means I need to love clothes in a way that doesn’t create huge amounts of waste and use a disproportionate amount of the world’s carbon budget. It is obscene that 300,000 tonnes of fashion waste goes into landfill each year. It is the opposite of progress that the average number of times a garment is worn before it is retired has dropped by 36% in the last 15 years. (In China, that figure is 70%.) Loving clothes shouldn’t be a system based on throwing them away. Fashion isn’t rubbish.

However, what this article is absolutely not about is me lecturing you in sustainability. You’re probably much, much better than me, for a start. If anything, this is about me being more like you. It’s about me changing my column for this newspaper so that it better reflects the way almost all of us really wear clothes – which, on any given Saturday morning, is more about styling what we already own than buying a new head-to-toe outfit. So from this month on, I’m going to change what I wear and what I write about: every week’s look will include old favourites from my wardrobe and discoveries from vintage stores. There will still, always, be gorgeous hand-picked pieces that are available to buy. But we won’t pretend that’s the whole story.

From Katharine Hamnett and Stella McCartney to newcomers like Mother of Pearl’s Amy Powney, designers who are passionate about making ethical fashion have helped make sustainability cool and glamorous and newsworthy. (Should cool or glamorous or newsworthy matter? Perhaps not. But the reality is, they do.) Even so, a meaningful conversation about fashion and sustainability needs to include not just those lucky enough to be able to afford expensive clothes, but the average shopper. The woman who would love a pair of Stella’s new Vegan Stan Smiths (£235) but who has, say, £30 to spend and wants to treat herself. (According to the Office for National Statistics, of an average household weekly spend of £554.20 a week, £25.10 goes on clothes and shoes.) There is a very human desire to move with the zeitgeist, an optimistic inclination to keep turning over a new leaf, which drives our impulse fashion buys – and why not? The received wisdom is that you should give up those £30 buys and save for a once-a-year £350 blazer instead; but this is unrealistic, not to mention a bit patronising.

Sustainability needs to start with taking a long, hard look at the psychology of fashion. When I buy clothes, I am trying to buy a better-looking, cooler, more exciting version of me. Same as it ever was, nothing new in that. But what has changed is that the chasm between the reflection in the mirror and our Instagram-fed aspirations yawns ever wider.

Sometimes clothes can bridge that gap. At its best, fashion can be nothing short of miraculous. Do you know when you should buy a dress? When you try it on and start slightly flirting with yourself in the changing room mirror. I don’t mean full-on flirting: that would be a bit weird. I just mean that you look in the mirror and are pleased by what you see and find yourself, without thinking about what you are doing, giving a bit of a hair toss, smiling at your reflection. When that happens, you should definitely buy that dress.

But you know which dress you absolutely shouldn’t buy? The one you try on, then look in the mirror and think, this is a great dress and if I lost two kilos I’d look nice in it, I wish I hadn’t eaten cake. That dress is negging you. That dress is not your friend. Please promise me you will never, ever buy that dress.

I have been asking lots of people who know about this stuff – thought leaders in fashion psychology, experts on the circular economy, women who are ninja-level at finding treasure in charity shops – for advice about how I can keep the fashion bar high when it comes to the clothes I wear and write about, while reducing the environmental damage.

Caryn Franklin, professor of diversity at Kingston School of Art, strikes a chord when she brings up the emotional aspect of sustainability as a particular issue for women. “Women feel they will never be good enough, that they must keep on striving for an ideal they will never achieve,” she says. “They medicate with clothes, using them to create the self they think they need to have – and when the dress doesn’t deliver they keep on disposing of clothes along the way.” In other words, there is a self-worth gap in our culture, and clothes dumped as landfill is the consequence.

You might think it a stretch to argue that building a look based around the clothes you already own is the first step towards accepting who you are. I don’t, actually. For starters, this is how 99% of us actually dress, most of the time. We need to stop calling it “recycling” when the Duchess of Cambridge wears the same coat twice, because it’s ludicrous; not talking about the fact that almost all of us are still wearing clothes we’ve had for years creates a weird dishonesty gap. And I don’t mean Granny’s cashmere (humblebrag 1.0) or a designer piece that now counts as vintage. I’m talking about wearing ordinary clothes, many years later, because you still like them. The black trousers I’m wearing in the photograph above came from Gap in 2006. I have worn them roughly once a week, sometimes more, for the last 12 years.

Nonetheless, my experience is that, when you think in terms of cost per wear, expensive clothes tend to end up as good, or better, value than the cheap stuff. The leopard-printed, short-sleeve jacket that’s hanging behind me in the photograph overleaf I bought from Betty Jackson in the very early noughties. I remember deliberating over it, because it wasn’t cheap. I mean, how useful is a leopard short sleeve jacket going to be, I fretted? Reader, I’ll tell you: very bloody useful. I love that jacket to bits. The paisley-printed blouse I’m wearing with the satin trousers on the previous page is by Louis Vuitton. It’s about a decade old; it comes out to fashion week every time there’s a boho thing going on (which is every year or two); and in fallow seasons, it’s a beach cover up, or a weekend lunch with jeans and boots favourite.

Jumper, £99, marksandspencer.com . Skirt, Jess’s own. Heels, £80, dunelondon.com . Hanging up: jeans, Jess’s own; Jess’s leopard-printed Betty Jackson jacket, nearly 20 years old and ‘loved to bits’. On floor: boots, £135, dunelondon.com

The blouse I am wearing with the Gap trousers is a vintage piece by Lauren, a Ralph Lauren brand, discovered on sale at Rokit for £30 by the Guardian’s brilliant stylist, Mel. I have never mastered charity shopping, so on a mission to gen up, I asked fashion styling supremo Bay Garnett, who creates cult capsule collections for MiH jeans based on her vintage denim trophies, for advice.

“When I go into a secondhand shop I look for what feels modern,” she says. “I hate the retro look.” This attitude is a revelation to me, because the retro look is exactly what puts me off. That hipster 1950s vibe, with the full skirts and the lipstick and the ironic hairstyle: great on other people, categorically not for me. “Oh God, me neither,” Garnett says. “I hate that idea of vintage shopping as something quirky and nostalgic and twee. I don’t actually like the word vintage at all. Recently I’ve bought some amazing 80s pieces, like a biker sweatshirt with a zip.”

Some of my favourite clothes have been brought back from the dead many times. The tiger-striped pencil skirt I’m wearing in the picture on the right I bought a decade ago from Max&Co, a MaxMara diffusion line; it was not designed for my habit of running up stairs two at a time and has had to be reconstructed several times. I had a mini-length slipdress covered in pink sequins (hey, it was the noughties) converted into a stretchy below-the-knee cocktail skirt five years ago and I now wear it to the kind of parties that call for a sparkly skirt and a nice sweater.

Lulu O’Connor, who runs online alterations company Clothes Doctor, is passionate about helping women enjoy their clothes for longer, and reels off a list of suggestions – many of which you can do at home. An oversized T-shirt you are attached to that’s lurking in the in-case-I-paint-the-house pile, for instance, could be that cropped-at-the-waist T-shirt everyone on Instagram is wearing with high-waisted trousers. (The more slogans and logos you chop through the middle of, the more Guccified the look.)

Mother of Pearl’s Powney recently launched a sustainable, ethical, seasonless capsule collection called No Frills. With price tags from £90, the range is keenly priced for a designer label – and the quality and label give it resale value, something Powney and other designers embracing the circular economy are passionate about. Vestiaire Collective – a sort of blue-chip eBay, just for fashion – is a great resource to find the person out there who wants to pay good money for the designer handbag you don’t use any more, freeing up your cash for a new one. The circular economy is picking up gear at high street level, too: John Lewis will buy back old clothes you have bought from them and no longer wear. An online calculator tells you how much the clothes you want to return (including socks) are worth; once you have £50 worth, a courier will collect them and bring you a voucher. Items are either resold (though not in John Lewis) mended or recycled.

This season, postpone that shopping trip. Put your keys down, take your coat off, make a cup of tea and open your wardrobe instead. Start by pulling out anything leopard print: these seem to get better with age. Any skirt that hits below the knee is good: if you’ve got a short-sleeve shirt- especially one of those garish, touristy ones – try it over the skirt, cinched with your widest belt. If there’s a pair of cropped trousers that you usually only wear on holiday, try them with ankle boots.

No doubt there is a much better, much worthier fashion column that could be written, about how we all have to stop shopping completely. Bagsy not writing that one, though. I am not ready to give up fashion. But I am ready to try and do it differently. What do you need to buy this season, to keep up with the times? That’s simple. Less.

How to get more out of your wardrobe

Do your research

The free Good On You app is a useful guide to everything from vegan materials, to how a brand is performing in terms of labour conditions or animal welfare.

Spotify your outfits

Plan your social calendar and rent accordingly. For serial wedding-goers, it’s a no-brainer: Wear The Walk offers a wide range of designer dresses and accessories; while Girl Meets Dress / is more mainstream (and also rents maternity wear: a great idea).

Recycle your run, and invest in ethical sportswear

Check out Contra, the new brand brought to you by the people behind Parkrun, which is ethically produced, non-gendered and body positive. Runners Need will recycle your old trainers all year round; but from 14 October–29 November there is the added incentive of a £20 voucher in its stores. For trainers that will biodegrade, try new Italian brand, Yatay –, – though they’re not cheap (from £220 a pair).

Spend less time shopping, and more time making

If you have the skills and time, The Maker’s Atelier offers beautifully designed dress patterns, alongside specially selected fabrics.

Recycle

The majority of our textile waste (66%) goes to landfill. Traid will collect for free from homes in London and some surrounding counties, including Hertfordshire, Surrey and Brighton. Book a collection at traid.org.uk/23collect.

Tips: Tamsin Blanchard. Hair and makeup: Sam Cooper at Carol Hayes Management. Shot on location.

• Jess’s new column starts on 19 October.

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