OK, so you're on Facebook, maybe LinkedIn, possibly Twitter, or maybe some other social media sites. Cool. The fact of your presence on social media sites is fine, but just being there is like opening the door to a room full of people (and here we're talking about potentially millions of people). So once you're in the room, what do you say?
Well when you walk into a real room the first thing you usually do is to greet people and say hello. It doesn't work the same way with social media, in part because usually no one's going to say hello right back (this isn't chatting or texting). Also, because most social media updates are short - you don't want to launch into a long harangue or statement about something - save those for your blog.
So what do you say? Well, keeping in mind the business reasons you using social media in the first place (your "why"), what you want to accomplish (your "what"), and how you've chosen to present yourself (your "who"), you might have a thought of what you would like to say, but I suggest first you hang out a bit and see what works.
When you first "get on" a new social media site, the best advice is to observe for a while. Follow (or 'friend' or 'link to') some folks, and watch what they do and say on the site. If you see a comment you like, say so, or maybe contribute to the discussion - but start your contributions slowly. Eventually, as you get to know what's acceptable and normal for a given social media site, start to share new topics or opinions.
This is the order: observe, engage, share. Of course you can jump right in and start to contribute, but what if your messages miss the subject mark, or the acceptable tone, or pacing?
Remembering to stay within the reasons you are using social media in the first place, start with just a bit of caution and then, as you gain confidence (and followers) pick it up. Certainly there's room for individualism, but if you're using social media for business, it pays off to find out what's acceptable and what works for others in businesses similar to yours.