There aren’t many. But here’s a few that should help us all:
1. No libel. Having practiced libel law, I am the sole judge of what is and isn’t.
2. Stick to the topic, please. Being wildly off-topic, or getting into a long and boring fight with another commenter, is a good way to be asked not to come back.
3. Don’t overpost. If you are posting more than ten comments a day, you are posting too much. You will be encouraged to start your own web site.
4. Be honest. People who use their real name, with verified email addresses, will get favoured commenter status. People who hide behind aliases and fake email addresses won’t.
5. Bad behaviour will be punished! Similarly, no promise is offered, express or implicit, to keep identities and identifying info secret. If you try to post something very offensive, libellous or worse, expect to be named.