One of the biggest things you can do to get more free traffic is to repurpose your existing content. What that means is to take existing articles, and transform them into different types of media (in this case, pdf files or word docs) and then re-distribute them to different sites that accept these new forms of content.
One of the best ones is scribd.com. In the video below I talk a little bit about how I took an existing article and turned it into a pdf, then uploaded to scribd. Enjoy!