Be sure to have lots of food on hand so that your guests do not drink on empty stomachs. Consider using a noncarbonated base, such as fruit juice, if you plan to serve an alcoholic punch, so that alcohol is absorbed into the bloodstream at a slower rate. Be sure to have plenty of nonalcoholic drinks available. Create an environment where people who don't drink alcohol won't feel pressured to do so. Serve as few salty snacks as possible.
Thirsty guests tend to drink more.
Plan lots of group activities, such as party games, to keep the focus of the party away from drinking. Before the party begins, have your guests determine designated drivers who will not drink any alcohol. Close the bar 90 minutes before the party ends. Serve coffee and dessert for the remainder of the party. If any guests have had too much to drink, arrange alternate rides home or invite them to stay over.