I know our clients get tired of hearing this, but I can't say it enough: social media is about networking and building relationships, not about broadcasting your own message incessantly. Nobody cares about you and your product. They care about how you can help them - whether it's solving a problem or just having fun.
My friend Ben Capozzi is a good example: he followed a link in an email to read a story by an awesome artist whose work he admired, then reached out in the blog comments section saying he enjoyed the story. Then he tweeted the story to his followers. Guess what? The blogger followed him back after that, and Ben ended up being asked to participate in a project he was doing. You just never know who you might meet through social media, just like you never know who you might meet at a party.