This is really a guide for teenage girls to throw a good house party (and not get anything broken)

[edit] Steps

Make sure your parents will be out of the house for the entire weekend! If it is just for the night chances are they will come in early or phone you that they will be there soon.

[edit] Planning

Tell about ten to fifteen people about the party, and soon the word will spread. All in all, it's likely fifty to seventy people will show up
Make sure all the good china/ornaments are stowed away safely, and that any rooms you don't want people in are locked
Make sure you have lots of food. Things that cater for all people; vegetarians, vegans, light eaters, heavy eaters etc.
Try to keep alcohol to a minimum, unless you want your friends being sick all over your carpet!

Play good music that everyone can enjoy, preferably Hip-Hop, Dance, Club or R&B. Nothing too heavy or too slow!
Be sociable! Keep yourself moving and talk to every one. If someone arrives that you don't know (friend of a friend, for example) try to get to know them a little better and if they are making a mess ask them to leave.
If something does, sadly, get broken, or someone makes a mess of a room, don't fret. If you get angry, or start chasing around after people with a broom, people will get sick of you. You can tidy up later!
If there aren't too many people, perhaps suggest a game of spin the bottle, dares, postman's knock or seven minutes in heaven. These games can be a lot of fun.
When the party dies down, and most of the people have left, there will definitely be a five or six random people hanging around. Try to politely get rid of them, nothing more interesting's going to happen

Get straight to tidying as soon as the last guest leaves (not before!). Your parents will be coming back tomorrow night (or maybe tonight, depending on how long the party lasted). Get the worst of it cleared away and then go to bed!
In the morning, have a tidying frenzy. Do one room at a time, and break that room into four manageable quarters- doing a bit at a time
Don't make it too tidy or your parents will be suspicious. Leave a few packets of crisps around, have some dishes lying in the sink...

If you want this to be quite a quiet gathering then don't just let the word spread, tell exactly the people who you want to come and exactly that they shouldn't tell anyone else about it.
Your diary should be stowed away with the valuables too; don't want someone reading that!
Ask people to bring their own CDs; someone will probably take charge of the CD player so you don't need to worry about changing them
If something gets broken, gather up the pieces. You don't want someone stepping on them, now, do you!
If you are playing spin the bottle/dares etc., then make sure everyone is playing. If half the people are playing and half the people are running around laughing and going wild,it will be very distracting!
Set an alarm so you don't sleep in too late. You need to get to tidying fast!

If some complete strangers show up at the door (and especially if they are much older than you/look like a bad crowd) just say "Sorry, I don't know you" and close the door. You don't know what they might do.
Keep the music volume down. You don't want the neighbours to complain, or people to have to shout over it.
Don't act suspicious when your parents arrive back, just chill out and watch TV.