Make sure it's not going to get gatecrashed!
I don't know if it's an Australian thing, but when a party gets out of control - it gets out of control BADLY!
My housemate had a birthday party for her 17th at her dads house and there were about 300 people running around trashing the place, stealing things and starting fights. In the end there was a big brawl with police officers in riot gear and even one of those fancy cop helicopters that have the big search lights. To top it all off someone got stabbed.
So not to be a party pooper but make sure it's not to huge, and make sure people know that while partners are welcome - idiots are not.
Don't be afraid to say no to people if they want to do something stupid in your house (one of my favourite disasters at my old place includes a mud party in my living room... I woke up to footprints on the ceiling). Remember it's your house, and your friends should be acting like guests - not like they own the place.
Make sure there is lots and lots and lots of toilet paper spare in a cupboard somewhere. Nothing ruins a party faster than no toilet paper.
Get plastic glasses. They don't have to be tacky ones that you would see at a kids party - you can get some really nice looking ones if you have a look around. Drunk people = smashed glass. Smashed glass + drunk people = bad accidents.
Also make sure there is plenty of room for people to crash if need be, the last thing you want is a group of people trying to drive home drunk. Places to crash for drunk people don't need to be beds... From what I've seen a cushion will do the trick, along with more bizare places for the drunker elements - bath tubs, rugs, linen cupboards etc.
And the most important thing - be a good host. Don't get to drunk to early because it will make people feel uncomfortable if they're just arriving (to see you!) and you're stumbling around changing the song 30 seconds in because you've got bored of it. If someone looks bored then introduce them to other people. Make sure people always have a drink in their hand (even if it's just water)
Oh - and a side note - think about what smokers are going to do if it's pouring down with rain and you have no shelter outside - it will easily ruin the party.
Wow, so I've talked about a lot here, but basically HAVE FUN! (And make sure you let us all know how it goes)