I'm in need of some tips...

try some traffic exchange sites and also microworkers.com that's a great way of doing it.

I'm also very interested in this because in a coulpe o months i'll be making one.
does your forum belongs to a website? There are lots of companies that you can affiliate with it all depends on the forums topic. amazon and ebay are always good, to have.

Metatags/meta description is very important to helping to get you to being found in places like Google. It's also a good idea to submit your site to google in general, and then upon being accepted go to your webmaster tools(you need a google account for this) and submit your website there, and then from there submit a site map. There are sitemap builders on the web if you don't know how to use one. What a sitemap helps to do is to kind of get an idea of the layout of your site so that google can crawl you better. The better you're crawled and the more "keyword-friendly" topics you have the more you'll be noticed. You can also try making a blog & submitting articles about whatever your subject and pinging your blog. Pinging your blog basically alerts google and everyone else your blog has fresh content, and then you just bounce the traffic you get from there into your forum. However. In general, getting really dedicated members takes time and building up. It won't happen overnight. If you have the money to spare, you could always do a paid to refer progrma. Whhere for x number of people brought in you'll pay x number of dollars or something like that. Anyways, those are just a few ideas. Most of the stuff mentioned above you can simply find guides on google for. Anyways, g'luck:)

I am also thinking of having such a site/forum of myself. Please remain in touch. Who knows we might be of any help to each other. Please add me as your friend. I have already added you.