Maybe this is indicative of why we Brits are not built to complain. Perhaps we are all wired up wrong, psychologically. But when I came across this infographic recently, my first thought was not: "It's about time someone taught restaurant staff how to handle complaints", but: "Come on, restaurant industry, grow a pair." Issued by US company, Provide Support, it is a 10-point guide to handling complaints, which fundamentally boils down to one supine dictum: the customer is always right.

But are they really? You do not have to spend long in and around restaurants to realise that the customer is often a bit of an arse. The British do not seem to complain about a problem so much as snap, suddenly flipping from tight-lipped disappointment to a state somewhere between incoherent self-righteousness and outright aggression. Customers need guidance in how to complain effectively, not vice-versa. So here is Word of Mouth's essential primer:

Don't gripe drunk

Obvious now. Less so when you are two bottles of wine in. Remember: florid body language, misguided attempts at humour and (a garbled) repetition of your complaint will likely inhibit rather than hasten a quick resolution of the problem. Let the designated driver handle it.

Ask to speak to the manager

Not because you are a pompous berk who always demands to speak to "whoever is in charge", but because 73.4% of all problems in restaurants originate in poor organisation, training or recruitment. The waiting staff are often innocent victims in the crossfire.

Get to the point

Don't start your sentence with: "Sorry…" What are you apologising for? Make your case politely but plainly. Have a fair and reasonable idea in your head of how you want the complaint dealt with (ie dish re-cooked, removed from the bill etc). If what you are offered is unsatisfactory, state your case in simple terms. You cannot moan about how you were only given a compensatory coffee for a ruined chateaubriand if, at the time, you meekly said, "Thank you." Restaurants are not in the business of giving free stuff away, but generally they do want to keep customers happy, particularly if that customer can make their case persuasively.

"Note to self: spit in table four's soup" Photograph: Juice Images / Alamy/Alamy

Put yourself in their shoes

With waiting staff, learn to differentiate between genuine rudeness or laziness, and their being, as it is colloquially known in the trade, "in the shit". Booking systems crash; restaurants get a sudden rush of walk-ins; staff walk out mid-shift. Look around you. Are you waiting for your drinks because the staff are chatting by the till or are they dashing around because they are evidently understaffed? Picking on people who are clearly having a hard time of it is tantamount to bullying. See also accidentally spilled drinks etc, even if you end up spattered. If the staff apologise, why rant? Haven't you ever dropped anything?

Don't talk to people as if they're idiots

An imperious tone will get you nowhere. Specifically, invoking your superior knowledge of how dish Y should be cooked or drink X served, in the manner of a lecture, is the behaviour of a prize twerp. If you want something done in a specific way, ask for it. Good restaurants will acquiesce. You do not need to prove your credibility by referencing your regular holidays in Tuscany/best friend who is a sommelier/how they serve asparagus at Le Gavroche. This isn't a competition.

NB Please also bear in mind that you probably don't know everything. Here are a couple of things you only do once: demand to know why this fish is still raw ("It's ceviche, madam.") and/or send back a bottle-conditioned beer because it is full of mould. The squirming embarrassment, however, will stay with you for ever.

There is bad cooking… and there is different cooking

Wild overseasoning, missing key ingredients, cold or burned food: these are all legitimate reasons for complaint. The fact that a dish has not been made "how you like it/do it at home" is not. Unless you can see double the amount going out to the next table, the same applies to portion size.

The menu is not optional

You want a dish served without one of its components? Within reason, that is fine. You want your steak cooked until it's incinerated? That is your prerogative. However, if you want spaghetti bolognese and it isn't on the menu, that is too bad. Likewise, you cannot expect the staff to nip to Sainsbury's Local to get you some sliced white bread because you don't like the chef's walnut loaf, or expect a place clearly not geared-up for cocktails to rustle you up an old fashioned (when you can't even remember the ingredients). The restaurant is not at fault, you are.

"Haven't you got a picture menu?" Photograph: Alamy

"Oh no, not TripAdvisor!"

Seriously, don't be That Guy. You know, the one attempting to – is this too strong a word? – blackmail the staff with the threat of writing a bad review on TripAdvisor or your pitiful blog, if they don't comp you this, that and the other. Attempting to throw your weight around like that, you lose any moral high ground. In fact, stay off TripAdvisor, at least in the aftermath of a bad experience. If your complaint hasn't been satisfactorily resolved on the night, email the restaurant. You will be amazed how receptive restaurants can be.

Don't struggle through

Don't persist with your off pint or your gritty mussels until you are halfway through, then complain. That looks like something else entirely: blagging. Similarly, there is no point telling the waitress clearing the table that there wasn't enough gravy. Speak up while the error can be corrected.

Know when to walk away

Sometimes you reach an impasse. There will not be agreement. Or closure. For instance, I was once told, after asking a waitress to ask the chef, that, no, there wasn't any spices or curry powder in my kedgeree. And that is how it should be. Lose your rag and what will that achieve? Except ruining the night for everyone you are with. Have a drink, calm down, and never go back. If only for the sake of your own sanity.

So, how do you complain? And what have you found it achieves? An eagerness to please ... or stony intransigence?