The FAQ already has these, what more would you suggest?
Keep personal information private. All posts in the forums are easily found via search engines, so unless you're willing to expose your information to the world, please do not post telephone numbers, e-mail addresses etc in your posts.
These are not concrete terms with precise definitions — avoid even the appearance of any of these things. If you’re unsure, ask yourself whether you'd go on TV and publicly say it on camera.
The Internet is Forever
Before you post, please think carefully about what you post. These days it’s good business practice to Google your company name every so often to see what people are saying about you. For that reason, if you’re asking for basic advice on how to deal with a difficult client, it would be prudent to avoid naming them.
At SitePoint we accept that occasionally people make silly mistakes and we’ll do everything we can to help you out, but we simply lack the time to edit hundreds of posts and heavy edits or post deletions compromise the flow of a discussion. So please, think first.