The simple way to view a backlink is as though it is a recomendation.
In the real world, if you need a plumber, you can either pick an unknown one from the yellow pages (if you've still got one) or you ask a friend. You will always trust the recomendation over the ad every time. This is how google views your site. The more recomendations, the more importantly google views your site and the further up the rankings you will go.
The key to backlinks is that they must be 1. Relevant and 2. Have authority.
Getting the relevant backlinks is relatively simple, getting the authority ones is a bit more complex.
Get the relevant ones first via article marketing and social bookmarking first, then go searching for authority sites in your niche that let you backlink.
Sounds simple, but it is hard work, have fun!!