Don't post to attack users or start arguments.
If you want to, you can post a link own website in your profile and within your signature (don't make it distracting if it's in your signature). Of course, you can post a links to websites when it positively contributes to a discussion.
Speak English. Do your best to use correct spelling and punctuation. Dont's: DON'T SHOUT, use excessive punctuation!!!!!!!!!, or make text too small or too big.
Try to add something to discussions. If you agree or disagree with something, explain why.