I have a friend who embarrasses me in restaurants. He does the same thing every time. Which is to call for the bill and pay the bill. Sometimes he might even, in some subtle way, draw attention to his tip. 'Did you see the tip there? Ah, bon. Merci.' Did I mention he is French? It doesn't matter. Anyway, here it comes. Once the waiter has given him his receipt he orders a coffee. 'Can I have a little espresso, please, and maybe one for Jan, too?'

It's only a small thing, but every time he does this, I want to kill myself. Of course, he does it to get free coffees and he thinks he is being fantastically crafty. It usually works, too, even if the waiters and waitresses know exactly what he is up to. For, believe me, they have seen every trick in the book, including the inappropriate purloining of linen napkins, customers who steal the cruets and couples who are planning on getting cosy on the cigarette patio when no one is looking. 'Sex to go on table four,' waiters will whisper to each as they are busy violating my French friend's free coffee in ways I don't want to think about. Meanwhile, anyone in the corner eating steak frîtes with questionable table manners will be noted and commented upon.

'Raised by wolves,' a waitress will confirm to her team, as she whisks by with a tray.

So never underestimate your waiter. Convention dictates that he or she must operate under a suffusion of polite compliance as they take your order and serve your meal. Yet under that façade of courteous dispassion, you are being clocked as assiduously as a criminal profiler. Yes, they may be looking out of the window while you hesitate over the roast guinea fowl or the braised beef with cabbage, but their focus is entirely on you. Big tipper? Asshole? The kind of diner who is not going to leave the table until every cube of sugar and packet of mustard is safely stowed inside her handbag? Lady, you are being graded and weighed like a bag of flour, be sure of it. Gents, they have already guessed exactly how much is in your wallet, right down to the nearest sixpence. Unless, of course, the waiter really is just looking out the window and thinking; I wonder if Olivier really does love Kylie. That can happen, too.

So try to be kind to your waiter or waitress. Every night, in a hundred different restaurants, some boorish customer is making the most of his only opportunity that day to tell someone else what to do. Appalling. He doesn't understand that news of his unpleasantness will be quickly semaphored around the room to other staff. Perhaps he will never realise that there was a reason why his steak was cold, his ice cream was hot and that tray fell on his head. So always treat your wait staff with respect, if only for reasons of self-preservation. If you ascertain they are from Italy, do not immediately ask: 'What part of Italy are you from?' only to lose interest when they tell you, because you have never been to that bit. They hear this a thousand times a day, and are sick of it. If they are from Eastern Europe and are pretending to be from Paris because the restaurant manager has insisted that they do this, do not quiz them on the back streets of the third arrondissement and that divine fromagerie where you bought the wet Roquefort. And stop being so blimmin' pretentious, while we're at it.

Don't forget that waiters never forget you. Your long-chain customer DNA has been processed into their mental database, with key details highlighted. Oh no, it's that guy who always takes three hours to choose a bowl of soup and complains that we never have white pepper. Drat, here come those freaks from Observer Food Monthly to drink the bar dry and share one bowl of chips between eight of them. Listen, after 9pm, just pour neat Sarsons into their wine glasses. They won't know the difference.

The worst customer of all is the attention seeker. The person who can't make up his mind about what to order, and needs advice on everything from the type of mushrooms in the risotto to what colour of tiles he should choose for his bathroom. Never be this person. Finally, never be the last customer to leave the restaurant, which is something Lulu Guinness might consider embroidering on one of her bags. Don't ever think that it's OK to linger because there is one other table still occupied on the other side of the room. Both parties are keeping each other there on a seesaw of mutual selfishness. Your waiter knows this, and will never forgive you for it. Revenge will be his.

Three restaurants with trouble-free waiters

Dehesa 25 Ganton Street, London W1, 020 7494 4170

New tapas-style restaurant that specialises in charcuterie and cheeses imported from Spain and Italy. Communal tables make it too noisy for serious water interaction, so relief all round there.

Foxtrot Oscar 79a Royal Hospital Road, London SW3, 020 7352 4448

First bistro from Gordon Ramsay. Potted shrimps, crab cakes, rib-eye steaks and Foxtrot fishcakes. The waiters will probably be far too scared of Gordon to bother about you.

The Seafood Restaurant 16 West End, St Monans, Fife, 01333 730327

Overrated restaurant with 'modern Scottish' cooking - you can interpret that as sloshing flavoured oils about and the occasional addition of a rogue ingredient to make it seem worth coming here. Nice waiting staff who grit their teeth when asked what part of Scotland they come from.

· These restaurants and hundreds more are on Jan's restaurant website areyoureadytoorder.co.uk