Link building inside pages

Link building isn't something I've really bothered about (maybe a couple of half arsed attempts). I had a bash today and

managed to find some great quality sites willing to put up some links for us.

All my subforums do really well on Google for the subjects they are targetted at. My question is:
Should I just target the frontpage with various phrases, or target the subforums (with subject specific keywords)?


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