'Tis a thing of extraordinary beauty!
Why would you even want to start a forum when there are already huge, great communities for pretty much every interest group out there?
Small communities don't normally succeed because of the lack of discussion. If you really wanted to start, I assume you'd have to get quite a few friends from a lot of different, larger forums and then have them help you set it up.
Plus unless you are going to spend all your time on the internet, the forum will take up lots of your time to manage it if you want to have a chance of having a successful forum. You might want to think about becoming a staff member on a preexisting forum and stick with that for a while and if you're still motivated then, then go ahead and start your own forum.
There's a sticky thread about running your own website/forum under the Technical Discussion [see Web help on top].