Here’s a very simple model for thinking about three main social media channels: your blog, Facebook and Twitter. I should say that this model applies in particular to solopreneurs and small businesses who are still developing their following and trying to use social media to do so. In this model the starting point is simply looking at who the audience is, since that helps determine tone, content and strategy.
The simplest version:
Your blog is for attracting a new audience, and providing value to your existing audience.
Facebook is for communicating with people you know, or at least have ‘weak ties’ with, i.e people that are already in your network.
Twitter is for actively finding and connecting with people outside of your current network.