If you're blogging or tweeting or posting to Facebook, you should be doing it to promote traffic to your website which is where the business happens. This article provides useful tips on creating effective 'link bait'.
If you're just using a social media channel for the sake of it - because it's what everyone is doing - you could well be wasting your time. Think about what you want your target audience to be doing on your website, and use social media to support this.
7 tips for creating great link bait - article by Webcredible