Clean the place: The house should be clean. Pick up all your crap. VACUUM! Mop your floor. Dusting is optional. Do all the dishes. Sober people don't like to party in a dump, and people come to parties sober, you do the math.
Prepare the outside of the house In the summer mow the lawn people shouldn't need a machete to get to the door. In the winter make sure you shovel and put some salt down.
Toilet Paper Chicks NEED the stuff so stock up. Have about two weeks worth on hand. Buy at least medium grade toilet paper the women will like it and you will appreciate it in the morning
Munchies: Prepare something for your drunks to eat. This becomes less important the larger the party but it is still good to have something on hand. Pretzels work wonders.
Non-Alcoholic Drinks: As silly as it seems some people don't drink, but anyway. To throw a good party you should have a good mix of drinks. A good assortment of soda would be good but make sure to include some diet, that will keep most people happy.
Provide a good mix of music: Depending on the amount of police visits you would like to have you should keep the volume moderate. Also don't play all the same style of music, try to mix it up a bit.
Provide enough Alcohol: Expect to be able to serve 5 drinks per person.
Try to avoid separating into groups: Keep people together, it makes the party a lot more fun.
Bring a Camera: You need to be able to remember the night somehow. Also tape recorders can be fun. Video Cameras are best but not everyone can afford that.
