Content! That's what has worked the best for me. Ensuring you have interesting and fresh content where you can talk about a particular area of your web site or a recent post of yours on social media. It won't just be for those that are interested in your content and click on your link whether Facebook,Twitter, Google+ etc. but you also have the secondary benefit of Google picking up your web site or blog content, your social media posts "and" those social media posts pointing back to your web site or blog are also a big plus.
As a bonus I'd also recommend that once you post something say on Facebook... that you also copy and paste it as a tweet, then onto Google+, then jump on Pinterest and capture your images (which also point back to your web site or blog) - more Google juice for you! This way you get the most bang for you time.
Lastly, I'd avoid completely "join my program", "make money here", or "earn from home" type links or posts via social media. Use the "soft sell" of content to bring them in, then let them decide if your program is of interest (via your text links or banners) once they arrive.
Wishing YOU the very best out there!