LIFE IS not fair. If it were, we wouldn't have had to invent etiquette, or the steel wool pad. But as it is, what with people always wanting to help you cook and most of the time being right where it is you need to be and blocking the knife drawer and elbowing the starter button on the Cuisinart, it's absolute hell to make your dinner guest feel useful as well as decorative.

If you set him too hard a task, he'll be embarrassed and the evening will be ruined. If it's too easy, he'll be insulted and the evening will be ruined.(Nobody promised you a rosefish.)

So you'll just have to feel your way into this part of the relationship, as if you were testing melons. The first time you invite a candidate, let him slice a loaf of bread or chop the celery, then watch the way he handles the knife. Ask him to stir the sauce: Does he splash like a kid in a mud puddle or roll his wrist through like Jimmy Connors? Have him turn the chicken.Does he lift and lay it down or stab it with a fork and drop it?

If, as occasionally happens, your intended beloved is revealed as a natural sous chef, the two of you may look forward to delicious nights of tine a tine romance. If it develops that he cannot put his hand in a drawer without sacrificing his blood to your cutlery, encourage him to investigate such complementary disciplines as bartending and massage.

Over the years, I have struck assorted bargains with regular dinner guests:

One was merely required to keep the wineglasses filled and Linda Ronstadt on the stereo, another to keep the manhattans frosted and read The Ear aloud. o

Setting the table is a chore to be reserved for long intimacy. Otherwise it's a copout, like giving your uncle a tie with little water spaniels on it. If worse comes to worst, let him run the garbage disposal.

Here are 10 chores to assign your dinner guest if he proclaims his expertise: (1) Bone the chicken breasts. (2) Beat the egg whites. (3) Peel the brocolli. (4) Filet the bluefish. (5) Roll the pastry. (6) Collar the souffle dish. (7) Drop fudge into cold water to form a soft balll. (8) Truss the turkey. (9) Shape the bagels. (10) Wash the endive.

Ten things to assign the guest who can scrounge his own breakfast: (1) Clean the spinach. (2) Wipe the mushrooms. (3) Skin the chicken breasts. (4) Grate the zucchini. (5) Beat the frosting. (6) Stick a chopstick into the oil to see if it bubbles. (7) Pound the veal. (8) Chop the onions. (10) Wash the romaine.

Ten things to give the guy who thinks boiling water requires a thermometer: (1) Break the bread crumbs. (2) Pour vinegar to the "V"line, add dry ingredients and shake. (3) Grate the cheese. (4) Squeeze the lemon. (5) Clean the strawberries. (6) Empty the ice trays. (7) Crumble the bacon. (8) Scrub the potatoes. (9) Husk the corn. (10) Wash the iceberg.

Ten things you'll just have to suffer through yourself: (1) Shuck the oysters. (2) Season the wok. (3) Mince the garlic. (4) Stuff the sausage. (5) Devein the shrimp. (6) Clean the sweetbreads. (7) Flame the brandy. (8) Drop the lobsters into the pot. (9) Season the curry. (10) Clean the oven.