You're right, NG is unique in a way because it offers everything - games, movies, music, art, a chat and a forum. I'm sure there's something here that you'll enjoy.
Some simple guidelines:
- Don't be more of a dick than everyone else (the bar is low, but it is there).
- Vote fairly on stuff.
- Earn experience and B/P points to increase your voting power (also see here).
- When making your own stuff, DON'T STEAL ANYTHING. Also make sure to report anything stolen (see the flag above a submission).
- Have fun.
- Don't eat anything anyone offers you.
- And when in doubt, consult the wiki, the FAQ, or the people on the Help forum.