netmeg - 5:08 pm on Jun 5, 2013 (gmt 0)
Learn HTTP status codes and how and when to use them.
Familiarize yourself with robots.txt and robots meta tags; learn when to use which and where (and avoid mistakes like using both!)
Remember sometimes what you keep OUT of Google is more important than what you put in. Things like search results pages and thin, low content or duplicate content pages that won't bring you quality traffic anyway.