Undermining the exagerrated fears of some SEO consultants about all the changes happening at Google Search in recent times, randfish over at SEOmoz Blog says -
SEO remains, at its core, remarkably similar to what it was in 2002:Make pages accessibleTarget with keywords that searchers employBuild content that users will find useful and valuableEarn editorial links from good sources
The Search Engine Optimization Starter Guide from Google has another nice advice -
..you should base your optimization decisions first and foremost on what's best for the visitors of your site.
Also see -