Be nice to other members. Even if you don't like them at all, you don't need to say anything. It's better to just say nothing than to say something mean or hurtful.
No swearing. It can be hurtful and offensive to some members.
No spamming. I think everyone can agree with me on this.
No double posting. If you have something to say, it can be said in one post.
Don't give out your or another person's personal information. First names are fine, but this is just common internet safety.
Don't give out your or another person's password. This is to protect your account from being hacked, and again, it's just common internet safety.
Only have one account.