Quality Guidelines from the Google webmaster guidelines
Google webmasters guidelines > Quality Guidelines (there are four basic principals and eight specific guidelines in this category)
The quality principles and guidelines are focused on things you can do to ensure your website is seen as a quality web presence. they also illustrate some specific things not to do.
still writing these...
- Avoid tricks intended to improve search engine rankings. A good rule of thumb is whether you'd feel comfortable explaining what you've done to a website that competes with you. Another useful test is to ask, "Does this help my users? Would I do this if search engines didn't exist?
- Don't participate in link schemes designed to increase your site's ranking or PageRank. In particular, avoid links to web spammers or "bad neighborhoods" on the web, as your own ranking may be affected adversely by those links.