Be consistent. 27 posts a day at the new fave microblogging site followed by 357 days of silence does nothing for your online presence. Pick a few social media channels and be there.
Be visible. In particular, be visible to your target audience. Choose a forum, platform, or community where your target audience hangs out. That may not be the same place your colleagues hang out.
Be sincere. The more adept your audience becomes with social media, the less tolerant they are of ulterior motives. Promoting your business is not an ulterior motive, by the way, but selling stuff in the guise of friendship is.
Be useful. Answer people’s questions when you know the answer, not just when your product is the answer. Share information.
Be entertaining. Share fun stuff as well as serious stuff, at least occasionally.
Be generous. Promote other people’s goods and services when you believe they’re the best. Share others’ good news when you find it interesting.
Be strategic. This doesn’t contradict the previous points. Make your decisions about where to put your business time for social media on the basis of data and goals. Once you get to the networking opportunity, be a good citizen of that community: it’s better for business.
Be appropriate. Have fun, be natural, enjoy yourself, but remember that your business is going to be around in the future, too. Don’t get so comfortable that you embarrass your future self.
Be quantifiable. Keep track of the response to your social media involvement — which means that you have to capture the information in the first place. So have analytics that measures traffic to your website from LinkedIn or Gowalla. Design test coupons at Facebook. You don’t want to discover how much you got out of your social media involvement only by how badly it effects your business when you give it up, thinking it wasn’t useful.
Be connected. Any social media you’re involved in should link to your website. It should look like your website. While it shouldn’t be filled with ads, it should mention your company sometimes, share your company news, and show your pride in your company.