"Link building" is a misnomer. Any links you "build" (i.e. create yourself) are essentially worthless -- or, at least, if they're not worthless now, they will be soon as Google gets even better at identifying and discounting these "self-made" links.
Instead of thinking about "link building" think in terms of "link attracting." Make your site as terrific as it can be -- informative, interesting, entertaining, beautiful to look at, fun (or at least useful) to read. Then use good old Marketing 101 to make sure relevant people know about it.
If your site is a top-notch resource and you get a few of the right people to visit it, the links will come. And they'll be real "editorial" links, the kind that Google loves (and the kind that bring you real, converting traffic, too -- apart from any "SEO benefit").