Keep it simple
Pick one wine that will appeal to most everybody and harmonize with the food you're serving. It should be young, fruity, food-friendly and not too tart.
A light-bodied red, like grenache or inexpensive pinot noir, served slightly chilled, works with almost any menu or buffet. If your guests don't drink wine often, a white wine with a bit of sweetness, like off-dry riesling or chenin blanc, will probably please them. In any case, don't feel obligated to offer several wines.
Keep it inexpensive
Wine doesn't need to cost a lot to serve its most important purposes: enhancing food and creating a festive atmosphere. Plenty of delicious wines -- even sparkling wines -- are available for less than $10.
Buy the right amount
Eyeball the guest list and count the kids and abstainers, so you get a good sense of how many people will actually be drinking. As a general rule, you can figure five glasses per bottle of wine (about 60 glasses per case).
People will usually drink more wine in the evening than the afternoon, and more Friday or Saturday night than Sunday. If it's hot and the party's outdoors, expect consumption to go way down.
Consider using actual wine glasses
Truth is, you can drink wine out of anything from a Dixie cup to fine crystal and still enjoy it. But if you're going to bother to buy nice wine, then it will show off to best advantage in glass. You can rent glasses inexpensively from any party supply store. For just a few dollars more, you can buy glasses by the case from a restaurant supplier for about $2 each (check the Yellow Pages). If you entertain often, that's a smart move.
Consult a wine specialist
Your local wine merchant or supermarket wine steward is an expert at estimating how much you'll need and helping you find the best wines for the occasion. Most wine merchants give a discount of at least 10 percent on cases of wine.
Don't get stressed out
Big events can be a headache anyway, so there's no point in letting your choice of wine make things worse. It's comforting to remember that unless your guests are real wine buffs, most of them won't pay a lot of attention to what they're drinking, but instead will be focused on enjoying your event.