If I don't know somebody I usually take a quick glance through their created threads to see where their interests lie so I can get to know a little something about them and what they do on the forum. I generally encourage them to get involved more and other little things like that. You don't have to write up a ton for every person, especially if you don't know them that well, or at all. I always try to say at least a little something. Good vibes and all!