Hi there. Are you doing SEO in your site? If so, social networking sites is the best platform to promote your site. To increase your traffic, you should make your post interesting enough and informative to drive them visit your site. And of course, you should interact with other users. Try to build a relationship between you and your target visitors. In that way, you can create a conversation healthy enough to boost your site.
yes amiyo are right. If you want to get good page rank then you have to promote of your site on different social network, forums, blogs. and also you have to make more back link by submitting social bookmark, directory submission as well as article submission.
You should focus on just one type of traffic generation for now. I found that doing multiple traffic generating strategies at the same time with limited resources on hand (I assume you don't have too much funds at hand to spend for advertising and outsourcing at the moment) is simply an overkill, it can quickly burn you.