Google has some nice guidelines for webmaster before they start SEO or website designing, which helps Google to find, index, and rank site. Even if you choose not to implement any of these suggestions, you should pay very close attention to the "Quality Guidelines," which outline some of the illicit practices that may lead to a site being removed entirely from the Google index.
You can visit below URL for the Guidelines:
http://www.google.com/webmasters/guidelines.html