High quality blog posts are by far the best and most natural looking backlings nowadays.
It's always good to have some link diversity though, so adding a good measure of forum links (and profiles), and some blog comments, don't hurt as they make your profile look more natural.
The bottom line is that there isn't a single method that will skyrocket your site on its own. You need to mix it up and think of how a real legit site with real users would naturally get backlinks.