Google Quality Guidelines for websites

Google Quality guidelines

Webmasters who spend their energies upholding the spirit of the basic principles will provide a much better user experience and subsequently enjoy better ranking than those who spend their time looking for loopholes they can exploit.

Quality guidelines - basic principles

• Make pages primarily for users, not for search engines.
•  Don't deceive your users.
• 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, or to a Google employee. Another useful test is to ask, "Does this help my users? Would I do this if search engines didn't exist?"
• Think about what makes your website unique, valuable, or engaging. Make your website stand out from others in your field.

Avoid the following techniques:

• Automatically generated content
• Cloaking
• Participating in link schemes
• Hidden text or links
• Doorway pages
• Sneaky redirects
• Scraped content
• Participating in affiliate programs without adding sufficient value
• Loading pages with irrelevant keywords
• Creating pages with malicious behavior such as phishing or installing viruses
• Sending automated queries to Google
• Abusing rich snippets markup 

Engage in good practices like the following:

• Monitoring your site for hacking and removing hacked content as soon as it appears
•  Preventing and removing user-generated spam on your site

If your site violates one or more of these guidelines, then Google may take manual action against it. Once you have remedied the problem, you can submit your site for reconsideration.