No messy foods. (So if it gets dropped and ground into the carpet, it can be vacuumed up easily)
Have trash bags. hanging open around the room for easy disposal of trash.
No movies/TV/computer games. (The point of the party is for people to actually get to know each other and have fun, not to sit and watch the boob tube.)
Plenty to drink, diet and sugared, caffinated and not. Alcohol, probably not a good idea. Don't forget the ice.
Wrap a washcloth over the lockbar to keep the door open. Put a sign on the door saying welcome and come it. when the party is over, put a sign on the door saying, sorry you missed the party.
No food that you have to worry about spoilage sitting out at room temperature for several hours.
Don't forget to have fun.
Tip the maid well for the extra mess the following morning.