I run a very new IM forum
www.martforum.com
Tell me few things that will enable me grow it within months.
The site itself looks okay, not stellar, but okay.
My advice for launching a new forum is to first assemble (recruit) a team of experienced people who are very knowledgeable about the subject matter. Ideally you want to have a dozen or more people right from the start. You can start with less, but it will take you a lot (lot) longer (probably years) to get the forum really cranking.
The idea behind forming a team from the start is so that you will have enough people who can contribute good advice and high level discussion right from the start. And it will allow you to have some real activity and lots of good content right from the start. Those two characteristics will make new visitors stick around and join your forum once they discover it for the first time.
If you don't have high level discussions and if you don't have an active community when they first land there, then they are less likely to stick around or come back for more at some other time. You want to suck them in and hook them right away.
Make visitors feel good about themselves. Make their experience on your forum as fun and enjoyable as you can make it. Then they will want to come back more often and be active.
I don't think it is worth promoting your forum much at all until you get that core team in place and make them moderators. Without that core team in place, a huge percentage of traffic you get to your site will simply bounce.