If your forum is small, (such as just starting out), would it be better to have an entire subforum dedicated to introductions or just one very long introductory thread where anyone new can make introductions?
Best to have an introductory forum, I feel. Believe me when I say that absolutely no one pays any attention to single stickied introduction threads. At most, the staff will post there occasionally since it's their job. Occasionally, a regular member or two will feel nice and welcome some new members as well. But most of the time, it goes completely unnoticed.
It's much more friendly as a community to dedicate an entire forum to new users. That way, each new member has their own little thread and regular community members can see whether or not they've been sufficiently welcomed yet. I myself also try to entice my own community into welcoming new users (for instance, if I have a forum cash plugin, I'll increase the payout multiplier slightly when posting in the Introductions forum.)
It goes a long way to making potential newbies feel more at home.
I always try and have an introductory board where I can, as has already been mentioned, it helps the new members to feel welcome and part of the community.
I've seen forums when both works. For introductions, though, a thread may be too crowded and not too comfortable to talk further. So separate threads for each member in one forum/sub-forum will be perfect.
However, as Red says, there are many ways to make a new member feels at home. 😀
I have a full board for introductions. I also stick it at the top so that its one of the first boards new members see. They don't have to post an introduction if they don't want to but I make it available.
An intro thread just doesn't cut it... People want to talk about them selves and they want others to connect with them and their passions and interested... making their own topic will make this happen. If you want active members, give them the tools to get what they want on your community.