That is a good question and the one I would like to learn more about myself.
However, I think the best SEO tactic is to provide good quality content to begin with. Search engine engineers aren't stupid, so sooner or later they would find a way to teach their engine robots to identify material that is flooded against pages that represent quality stuff. Google still does that quite well.
Another thing you can do is link exchange with other forums, build up search keyword relevancy around your site.
I know that at our forum. vBSEO worked well for a couple of months, but then declined in effectiveness. Primarily because so many other forums started to use the hack.
Best,