don't: fuck up the house. this may seem funny at the time but is seriously not cool (what if it were yours), its also a good way to not get invited again. if its at someones parents house even little things like throwing empties in the trash, not smoking inside and taking shoes off is very appreciated.
do: bring your own alcohol (especially), drugs, smokes, whatever. its fine to bum stuff every once in a while but everyone loves a giver.
do: don't be afraid to join in drinking games if you're north american even if you aren't familiar, people enjoy teaching.
don't: if you aren't north american the only game you need is drink, don't try to start some frat boy shit.
do: be a lover not a fighter, people who cause trouble are lame
don't: don't be that weirdo that goes just to fuck girls. people notice and its creepy. if it happens it happens - schwingg
do: meet new people.
do: get fucked up
dont: be that guy changing songs halfway through all the time. people do sometimes do this when hosts dont make a playlist or get a dj.
those are tips not rules, save those for work and school. go with the flow and don't overthink it, go craze, have fun!