You've long looked with awe upon the superhosts and wonderhostesses who can improvise a successful party seemingly without preparation. Now it's your turn. The Christmas-party you had thought about but never planned is suddenly upon you. You just have the neighbors over, or produce friends to meet your relatives from Topeka.

No caterers are available and there's no time to cook. Fret not. Here are a quarter of concepts to ease the pain of the last-minute party.

The One-Drink Wassail

Having friends in for a drink suits the season perfectly. But cocktails by themselves aren't special enough. You need to concoct something that passes as a liquid work of art. Hot wine punches are appropriate, but a lot of work. Keeping them warm is a problem; someone has to stand at the stove mixing up new batches. For the esoteric, a bottle of vintage port can be an object of worship. Add a Stilton cheese, crackers and a fruit such as pears and be prepared to hear a chorus of "Joy to the World."

For the rest of us, how about egg-nog? It's America's dairies that have given eggnog a bad name. That creamy, unctuous golden liquid that pours so easily into glass or bowl is too rich and too bland to be truly distinctive. One chubby cup's worth and your guests are asking for something else. Double trouble and triple work. The answer is to make an eggnog with hair on its chest. Strong, even formidable, it will have your guests calling for the "chef." Also, being strong, it will not be consumed in great quantity, so there will be no need to mix a tankcar full. (Those who intend to drink too much will do so whatever the strength of a specific beverage. A less-than-strong eggnog, with its creamy flavor, can mislead the unwary.)

The eggnog recipe recommended here are from Flavors , a cookbook published this year by the Junior League of San Antonio. Christmas cookies bought or made (see Marian Burros' story in this section) will be suitable companions.

OLD SOUTH EGGNOG

(About 40 servings) 12 eggs, separated 4 cups confectioners' sugar 2 cups bourbon 1 cup rum 2 teaspoons vanilla 1 quart heavy cream 1 tablespoon freshly grated nutmeg

Beat egg yolks until cream colored. Continue beating while adding 2 cups sugar, bourbon, rum and vanilla. Beat cream until it stands in peaks and add 1 cup sugar. Mix together in a punch bowl. Garnish with nutmeg. Serve immediately.

-From "Flavors," a cookbook of the Junior League of San Antonio

Bring It Along

His party is a natural during the week after Christmas. The gimmick is to invite friends or neighbors with the stipulation that they bring some item of food or drink of which Father Christmas has delivered an excess. You provide plates, silver, glasses, napkins and seasonal music-or a football game. They should arrive with collections of fast-aging fresh or exotic dried fruit, baskets of nuts, an oversized cheese or two, or wooden boards with small cheeses and meat spreads, fruitcakes or plum pudding, boxes of cookies from distant relatives, pepperjelly and other preserves made by other distant relatives, jugs of milk punch and bloody marys and, maybe, if you are lucky, a cured ham or a smoked turkey.

Wine & Cheese Connection

This classic entertainment is easily reduced to a formula: for each person allow 3 glasses of wine (12 ounces), 3 ounces of cheese and 1/2 a piece of fruit such as apple or pear.Ideally, the cheese should be purchased at a specialty shop with an eye to contrast in form and texture. A blue (Stilton or Roquefort), a soft ripening (brie or camembert) and a firmer cheese (gruyere) team up nicely. Buy French bread (the best available is at the Bread oven on 19th street NW) and slice it thin, or pick up unsalted crackers such as Jacobs, Carr's or Bremner wafers. Just remember to put out some knives for cutting the cheese and the guests will do the rest.

As for wine, most cheese shops are related to or located near wine shops. Jug wines do very well for a group. If you have some decanters, serve the wine in them and watch the would-be connoiseurs among your guests find signs of greatness in each glass. For something slightly upscale, try wines in outsized bottles such as Fetzer's Premium Red from California (about $6 for a magnum) or La Fleur Blanche, a French white. (Apex Liquors sells four magnums of La Fleur for $10.) Your cheese wines needn't be all red. Search out cheeses from white wine areas-Italy, Germany-or soft whites such as Havarti. If the temperature is right these days (from mid-30s to mid-40s), white wine can be chilled on a window ledge or a porch.

You may think therehs nothing new about wine and cheese these days except the very high prices cheeses command. But thanks to the food processor there is. Almost instant dips and spreads can be churned out in moments. One working woman claims that with a supply of Cheddar and cream cheese in the refreigerator, she can entertain even if guests arrive home with her. The cheese is mixed with herbs or spices and spooned into crocks or formed into a ball and rolled in crushed, leftover nuts.

With a little more time, stop at the supermarket. Pick up the aforementioned cheeses, wine, crackers, some yogurt and vegetables such as cauliflower, broccoli, carrots and celery. In a blender or by hand, mix the yogurt with herbs and spices to form a dip. Cut the vegetables and, if there is time, let them crisp in salted water in the refrigerator. Scatter them on a platter around a bowl containing the dip.

CREAM CHEESE LOG 16 ounces (2 packages) cream cheese, at room temperature 2 tablespoons grated onion 1/2 cup chopped pineapple, drained 1/2 cup chopped or crushed nuts

In a bowl, or in a food processor, work together cream cheese, onion and pineapple. When well blended transfer to a sheet of plastic wrap and form into a ball or log. Chill in refrigerator until solid. Prepare nuts (use leftovers if you have a bowl sitting out) and place them in a shallow bowl or on a plate. Unwrap cheese ball, roll it in the nuts until well coated and transfer to a serving plate. Surround the cheese with crackers.

SHIELA KATZ'S YOGURT DIP 1 container (8 ounces) unflavored yogurt 1/2 teaspoon tumeric 1/2 teaspoon ground cumin 1/4 teaspoon ground cinnamon

Mix yogurt and spices. Chill until shortly before serving, then place in the center of a platter, surrounded by raw vegetables such as broccoli and cauliflower florettes, carrot sticks, mushroom pieces and crisp-steamed brussels sprouts.

The Edible Centerpiece

You haven't time to do a lot of little dishes, so provide one big, eye-catching item and let the guests do the work themselves. Price and palate both enter the equation, but you might consider:

Pastries and coffee. This is ideal for an evening gathering after an event. You want it to be special, but you don't want it to last too long. You want the food to look nice, but you have to be at the event instead of in the kitchen. So be the first on your block to serve the products of master baker Philippe Laurier. His Palais des Friandises in the market area of White Flint Mall will sell you two magnificent 8-inch cakes for$32, along with four dozen hors d'oeuvres ( $20). That should serve, though not satisfy, a group of 20. Then stop by the Perfect Cup, also at White Flint, and buy a half-pound of butter-flavored Columbian supremo coffee and a half-pound of Columbian Almond (total cost, about $5.65). Brew them separately and offer a choice.

Oysters. One host, a do-it-yourself bug with a sense of humor, sponsors an annual get-together where those who want to eat have to work for what they get. He provides a large supply of fresh oysters in the shell (which represents a considerable saving over shucked oysters), oyster knives and work gloves. Sliced lemons, a peppermill, cocktail or white oyster sauce and paper napkins are on the table. He demonstrates the opening technique until appetities are properly whetted, then announces the guests are on their own.

On Maine Avenue last week Bay oysters were selling for $18 a bushel; Chincoteagues were $20. There are at least 20 dozen oysters in bushel, but judging quantities is difficult. Eating a dozen is only a warmup exercise for some; for others the last oyster comes before the first. Beer is a good accompanying beverage, so is chilled, very dry white wine.

Cannon's, at 1065 31st st. NW, will sell you oysters already shucked for somewhat more money. The cost is $3.30 a dozen, with shucked clams going for $3 a dozen. The Chevy Chase Seafood Market, 5509 Connecticut Ave NW, performs the same tasks. Cannon's also will send unshucked oysters (at $37 for each box of 240) to your home along with a man to shuck them (his fee is $55)

Smoked Salmon. Here's a showstopper. (So is caviar, but smoked salmon goes further and, as expensive as it is, is a relative bargain). All you need do is find as platter or wooden cutting board big enough to hold the side or piece of salmon, be sure your ham knife is sharp, butter some slices of black bread and put out lemon wedges carpers, chopped onion and, if you want to show off, sprigs of dill. The salmon, placed skin side down, should be slice very thinly on a bias toward the skin. Turn the knife and cut along the skin to free the slice the skin to free the slice Serve champagne or a fine chardonnay (it's too late to try to save money) or imorted vodka frozen into a block of ice.

Whagshal's, 4855 Massachusetts Ave. NW, sells smoked salmon for $17 a pound. Cannon's rpvie is $12.90, but the salmon is frozen. It is available in other stores as well and, for next year, ny mial for Seatlle, Scotland or Ireland.

Italian Cold Cuts. Vace, 3510 Connecticut Ave. NW., stocks the superb Citterio line of sandwich meats, made by the New Jersey branch of the Italian firm. You will want-sliced-mortadella, two kinds of salami, capracolla, ham and provolone cheese, Italian bread, plus some chopped hot peppers. The store accepts telephone orders. Estimate about $25 for a dozen people. At home you arrange the food on plates, shred some lettuce, slice an onion and a few tomatoes, put out salt, pepper, olive oil, Italian wine or beer and relax.

For the non-ritualists and fussy eaters among your comapny, you might have some rye bread, mustard and mayonnaise available.

WHITE OYSTER SAUCE

(Makes about 1/2 cup) 1/2 cup good quality, mild white wine vinegar 2 tablespoons finely chopped shallots or scallions 12 peppercorns, coarsely crushed

Stir vinegar with shallots and peppercorns at least 30 minutes before serving. If the oysters are bland, you may want to add some salt o the sauce. CAPTION: Illustrations, 1 through 4, no captions, by David Cain for The Washington Post