I'll give you my personal opinion on forum posting...
Don't post in forums strictly for "
SEO Value". Find communities you like and enjoy and try and be a valuable member of that community. What you contribute in the way of questions, answers, and input is what gives people a reason to follow your links to begin with. It's
what you post that matters not simply the fact that you do.
Like any community, online or off, you "reap what you sow".
Likely not the answer you were looking for but it is what I believe.
Dave