Okay, I might as well chip in.

1. Don't be stingy.
Let other people use your weed and if u rock up at a session without some weed (for what ever reason), make damn sure that u have plenty by the next one. I'm sorry if this offends anyone but I, personaly, am sick of people who come to a designated session without weed every time.

2. Don't be stingy.
If, for what ever reason, u can't get hold of weed for a session, bring extra munchies.

3. Be sanitary.
Don't wrap your lips around the bong.
Don't exhale into the bong.

4. Be social, chilled and relaxed.
Grab any chance u can to toke up with other people. You will be very surprised at how much fun it can be to smoke with someone who you have never smoked with before.

You would think that most of this would be common sense but you would be surprised at how many people defy them.