Here are four to start us off:
1. Don't keep repeating yourself, especially under ridiculous pseudonyms.
2. Don't open a discussion if you aren't actually prepared (in any sense of the word) to discuss anything.
3. Don't tell people what they probably already know.
4. If others have expressed it better than you ever could, direct readers to that source wherever possible, and try to allow people to come to their own conclusions and offer their own, presumably welcome, comments on what they have read before chipping in with your "wisdom".
Sorry, that last one got a bit long, but I couldn't be assed breaking it up into smaller points.
If you want to continue this list, please do so, but only from number 5!
