What steps can I take to diagnose a drop in ranking?

When you notice a drastic drop in your rankings and traffic from Google, what process would you take for diagnosing the issue? Ryan, Dearborn, MI Learn how to diagnose ranking issues: www.google.com Site: search and other operators: www.google.com Fetch as Googlebot: www.google.com Have a question? Ask it in our Webmaster Help Forum: www.google.com Want your question to be answered on a video like this? Follow us on Twitter and look for an announcement when we take new questions: twitter.com More videos: www.youtube.com Webmaster Central Blog: googlewebmastercentral.blogspot.com Webmaster Central: www.google.com