If you've been around for a while, be sure to introduce yourself to the newbies, and help make them feel at home. Do not talk to them like they are lesser than you because you have more posts than they do or have been on the board longer. We all started as newbies on the board and know how that would feel if it would happen to us. Feel free to lurk. You don't have to post messages to have fun on the board.
Some people enjoy reading the posts without posting anything themselves, which is fine.
Keep disagreements civil. You certainly don't have to agree with everyone on the boards, but keep your disagreements on topic. You can argue a point without being nasty. There is no reason whatsoever for name calling and rudeness. I am not going tolerate being constantly e-mailed with complaints that one poster attacked another.