I find ranking with videos the easiest and quickest method to get free traffic, since Google changed its algorithms.
Social media is becoming prominent is delivering significant traffic day by day so try to increase your social media presence along with building the relevant back links.
Social 2.0 sites such as reddit and facebook are still in the top percentage of most of my traffic sources. I get search engines traffic but not nearly as much from social media. It really depends on your niche. Some niches will blend in nicely with social media and some just don't.