Send messages: Find a reason to connect with the people in your network, and send them a message once in a while. Since the main point of this is to keep a channel of communication open, it doesn’t have to be profound — a “happy birthday” is good, if the site reveals birthdays. Don’t, though, make it all about you — that is, don’t post a message to everyone in your list every time you update a picture, go to work, or leave your house. (You laugh — I’ve had friends that did this!)
Have something to say: Let people know why you’re there, what your purpose is, and what makes you, you. Give people a reason to pay attention to you. Although most people in your circle will stay in your circle indefinitely if you don’t do anything at all, having connections because they’ve forgotten you’re there is hardly the best use of a social network! Post something to your front page, blog, wall, or whatever it is every now and then, so that people learn something about you.
Avoid clutter: Remember when MySpace pages were awful and Facebook pages were clean and simple. No more — now it takes about 8 minutes for your profile anywhere to get covered with junk. If your page is so full of junk that nobody can tell anything important about you, you might as well not have a page. Limit yourself to only 3 or 4 extras, and either stick with the default theme or try to find one that’s clean and simple.
Firewall your personal with business lives: This might not apply to everyone, but for most people, once you’ve decided to use a social networking site for business purposes, don’t use it at all for non-business communication — and vice versa. Remember that the story about you, the goat, and the magnum of champagne is going out to everyone you’ve allowed to see your profile. That’s not something you want to share with potential business partners. If necessary, create two profiles on the same site, one for your business persona, the other for your personal life; instead of denying friend requests from friends and family, you can just refer them to the other profile.
Social networking sites have a reputation as being huge time wasters, and for most people, they are. If you can afford that luxury, more power to you; for the rest of you, really think about what social networking can do for you and focus your energies to making that work.