if this is your first party you don't have to try and dress like a "raver" if you don't want to. you should just wear something thats fun and comfortable to dance all night. bright colors are a plus
i'm a fan of lots of pockets. i never seem to have enough places to carry all the crap i end up bringing/accumulating.
go to the *what are you wearing?* thread and read what some other people are wearing for some ideas. or go to the archives and check out the picture thread from past parties