social networking sites can bring in hordes of traffic but now the real meat of the site comes into action.
your visitors should not be just anyone but should be relvant to your niche and also your site should have content that can keep them stick to the page itself.
so what i suggest is start building a social network and don't start exploiting right away wat for some time and when you see the time is right then only start publicity. also network with people whom you actually would like to interact.
example twitter followers most of time time just follow you and will never pay attention to your tweets if you increase follower through some follow me if i follow you program.
but if you have acutally earned Followers by your content then definetely one link of yours will bring in a lot more the just plain traffic.
hope i am not mixxing a lot of things here