With social networks you are just going to have to constantly visit and leave valuable comments. It is a process and cannot be rushed. If you don't have one already, create a blog and invite the social network visitors over. Keep in mind the web is nothing more than a giant community. Meet and greet is the key.
I haven't had success yet with Twitter but with Pinterest and Tumblr a different story for me. I make money on both of them. You have to contribute something of value and you must also be different in your own way.
As the person said above ENGAGEMENT is key, in my opinion Facebook is garbage stick to Pinterest and Tumblr