Tactical SEO Framework
Ensuring your site is search-engine spider-friendly. Several SEO crawl analysis tools exist to help you quickly understand how accessible your site is to search engines, so you can diagnose potential crawling issues to fix immediately.
This full interview with Matt Cutts contains essential information.
PR(A) = (1-d) + d (PR(T1)/C(T1) + … + PR(Tn)/C(Tn))
http://infolab.stanford.edu/~backrub/google.html (Larry Page and Sergey Brin’s Stanford paper (on the Anatomy of Google’s algorithm, at least as it were when they built Google)
site architecture factors
What Causes a Page to Rank? (additional reading)