Wine in a wine store

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How Much Alcohol Should I Buy?
Few things can end a party more quickly than running out of booze. But alcohol can be pricey, so to avoid ending up with gallons of vodka, use these rules of thumb: Each guest will drink an average of two drinks the first hour and one drink each hour thereafter, and 40 percent will drink beer, 30 percent will drink hard liquor, and 30 percent will drink wine. When calculating quantities, know that a 1-liter bottle of alcohol yields approximately 22 mixed drinks. Evite's Drink Calculator lets you plug in the length of your party; how many light, average and heavy drinkers are attending; and what kind of alcohol you're serving. It then tells you how much to buy.
Cocktail shaker and lemons on a bar

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How Should I Set Up the Bar?
Having two bars positioned on opposite ends of the party sounds nice in theory, but that means you'll need to keep checking both throughout the event to make sure they're stocked. You're better off going with one long (6 to 8 feet) and fairly wide (2.5 feet) table, such as this $39 folding model from Wal-Mart. Set up a station on each end of the table with ice, mixers, garnishes and a towel; then put the liquor and wine (at least one bottle of each kind) in the middle so people can reach them from different angles. Near the bottles, place a cocktail shaker with a strainer (this kit also comes with a mixing glass with instructions on how to make a few classic cocktails and is only $13), an ice bucket and tongs, a wine opener, a bottle opener, a tall mixing spoon, and a jigger or shot glass. Set a trash can under the table.
Plastic cup

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Are Plastic Cups Okay?
Glass barware feels more special than plastic, but it's really only doable for small gatherings. If you're set on glass, there are deals out there on basic styles, such as this set of 12 glasses for $10. For larger groups, though, Mark Oldman, a wine expert known for his unsnooty approach, is fine with plastic—so long as it's clear. (You want to avoid what Oldman calls "the lollygag-around-the-keg cup" as well as "the dentist-style Dixie cup.") He prefers the taller, narrower cups over the shorter, wider ones; they're less likely to spill and can hold more wine or mixed drinks, so party-goers won't have to elbow their way through the room as often for a refill. Put cups or glasses and a big stack of cocktail napkins on both ends of the bar.
Bottles of liquor

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What Kind of Liquor Do I Need?
Jonathan Pogash, a former Russian Tea Room barback who now runs his own beverage consulting company, says all home bars should have vodka, gin, rum (go with a darker, aged variety for holiday cocktails), tequila and whiskey (bourbon or rye). Splurge on whiskey, since people drink it straight or on the rocks, but don't bother going premium with vodka, gin, rum and tequila, because partygoers will mix them with something else. If your crowd will likely have some martini or Manhattan drinkers, stock dry and sweet vermouth and bitters (Angostura is most common).
Pulling wine out of a box

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How Much Wine Should I Have?
Figure one bottle of wine per eight guests. Although white wine gets most of the love at parties during the rest of the year, when the weather turns cold, the number of red wine drinkers increases. Oldman's advice is to go with a 60-40 ratio so you have slightly more red than white. And sparkling wine is always popular at the holidays; Oldman favors inexpensive American or Italian varieties for large gatherings. (A 750-milliliter bottle fills six regular champagne glasses.)
Bottles of juice and soda

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Do I Need Fancy Juices and Sodas?
No, but you do need the basics: 2 quarts each of store-brand orange juice and cranberry juice should be fine for up to 35 guests. You should also have small bottles of lemon and lime juice. For every 35 guests, have 6 liters each of club soda or seltzer, cola, diet cola and lemon-lime soda, and 4 liters each of ginger ale and tonic.
Lemon, lime, olives

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How Should I Calculate Garnishes?
Plan on one lemon and one lime for every three guests. Preslice them (though not more than an hour before the party begins, otherwise they'll dry out) and keep the slices on the thin side to get more from each fruit. If you're going to put out the liquid ingredients to make martinis, you'll need olives too. Don't bother with cocktail onions; they're really only used in one drink (a Gibson). Instead, make up a small bowl of orange and lemon twists: Take the peel, roll it into a tube and slice it into 1/4-inch strips. Guests can use them in everything from dry martinis to vodka tonics.
Bags of ice

How Can I Make Sure I Don't Run Out of Ice?
Load up on a pound and a half per person, which will ensure you have enough ice for drinks and for keeping beer and white wine cold in an ice bath. Use about half your ice to make the bath by filling a cooler, tub or large bucket halfway, using one part water to three parts ice. Throw in a handful of salt to slow down the melting. Beer and wine should go in at least 30 minutes before the party starts. The other half of the ice can go in the freezer or a closed cooler; replenish the ice buckets on the bar throughout the party.

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