One of the smartest things I ever did to increase traffic was to take part in blog commenting. As long as you have something to add to the post you are commenting on (IE don't just leave a comment saying "thanks") then it will work very well for you.
You will have to patient and start building links doing forum posting and wait for the results if you have quality content you will see organic traffic growing also you can try to use social networks to expand your audicence
It takes time for the web traffic to grow as it takes time for the webmasters to post large amount of informative posts onto their sites. And it takes time for them to submit URLs to social bookmarking sites and social networking sites and get them cached by search engines. Based on my experience, when I launch a new site, the traffic to my site will grow by a hundred or two for the first few month, then by hundreds for another few month, then by thousand suddenly. So, for th starting stage of running a new website, just relax and focus on posting quality posts.