Here's a question I'm asked often. "I want to get Brand X started in social media. What should we be saying in _____________" (fill in the blank with the social platform du jour).
My response: "say nothing".
Until you know what your customers are saying and where they are saying it, do yourself a favor. Save yourself some embarrassment by spending at least a month doing nothing but listening.
You can hire a company to do this for you. Or you can take a DIY approach by setting some Google alerts and searching the social platforms you think your customers are using, like Twitter, Facebook, Foursquare, Quora, etc.
Keep your ears open and your mouth shut. Then spend some time thinking about what you've learned. What do your customers care about? How can you provide value? If you've done a good job of listening, you'll know what to say and where to get started.