Cheap liquors tend to taste harsh. If you must use cheap liquors, try to use them in cocktails containing fruit juices or cream. This tends to hide the taste. Never shake cocktails containing carbonated mixers unless the recipe specifically calls for shaking. This makes the cocktail taste flat.
Most people tend to get intoxicated faster when sitting down rather that standing or walking.
Keep this in mind when making your guests cocktails and adjust the alcohol content accordingly. You will find that younger guests will tend to want a variety of shooters and imported or specialty beers, while older guests will tend to stick to one type of cocktail or beer. Purchase the alcohol for the party accordingly.