This is pretty interesting reading from SEOMoz's 2009 survey. External anchor text links from trusted sources are King (no surprise). Other factors that I've previously read that are "must-have" (social bookmarking, etc.) are downplayed. These are only opinions from so-called experts, but they line up nicely with what I'm seeing in my own efforts.
Search Engine Ranking Factors | SEOmoz
Search Engine Ranking Factors | SEOmoz