Useful Videos

Google recommendations

If you want to do it yourself or you want to hire an SEO company to take care of your website is indicated to watch those videos and only after taking a decision.

SEO startups in under 10 minutes
Creating an SEO strategy
Using Search Queries to improve your site
5 common mistakes in SEO (and 6 good ideas!)
Using Webmaster Tools like an SEO
Site Performance For Webmasters