If you’re in a competitive industry and trying to achieve SEO success simply optimising your website for a set of keywords may not be enough. Google’s algorithms also use a number of off page factors to decide which sites should rank above others.
It has long been known that the number of relevant and authoritative domains linking to you are the major factor that boosts your websites external reputation, but there has been much conjecture about the effects of other external factors such as social signals and link building schemes.
What should you believe and what should you ignore?
Unfortunately Google doesn’t disclose the full algorithm they use but they have made a number of statements on their own blog and through social media comments that have enabled the SEO industry to form some kind of educated guess as to what helps and what doesn’t.
In short, as Google have said many times, create great content that people will naturally want to link to and avoid paid link schemes like the plague.