Now if it's your party that's another story... You look at the party list and you go out and buy as much booze as you have on hand cash. When you get home you start pruning the list based on the following guidelines:

1.) People who bring their own booze, this usually means that they drink like bastards and no way is the small fifth they brought gonna be enough for the both of them!

2.)  Other people.

Gary's Party Guide

OK, here's the way I see it...  If you're at another person's party you should follow these basic rules:

1. Hang near the keg
   
2. Never put your beer down for fear of losing the only cup you really want to drink out of.
   
3. Watch the front door for anyone who brings in anything besides beer and make sure you know where he or she hides it in the fridge.
   
4. Never...I repeat never leave early...I never understood this so it's just gonna stand.
   
5. If it's a BYOB make sure you have that dusty bottle of cinnamon schnapps... likely that you'll get to recover it again for the next party.
   
6. Always look for the DrunkenMaidŽ chair. It's usually unbreakable!
   
7. Keep an eye out for any drunks who are close to passing out. Once unconscious their booze is fair game.