In case you were interested in learning more about what not to do regarding SEO and trying to game the Google system, here are some articles about recents trends and events that might shed more light on best and worst practices.
The Golden Age of Spam Comments Has Ended
Google Downgrades Rap Genius Links from Lyrics Searches
The New SEO Rules in a Content Marketing World
And of course, Google has a number of documents explaining how to do it yourself and how to hire someone to do it. Here’s their one-page SEO Guide, for a brief overview, too.
Updated: Expedia too!