Saw a great slide in a presentation from SEOMOZ. What is interesting about this image is that it shows a Pyramid based on SEO and the sections which are part of it.
The key aspects from this image are that the foundations of the SEO pyramid are Content, Bot Access and XML site maps.
Keyword targeting is the next key ingredient of the pyramid followed by Link building which is one of the most important sections and then finally social is at the top, I think Social SEO will be even more crucial in the near future.
Image credit – seomoz.org