I'm doing pretty well.
One sale every five freesites isn't good. Do you concentrate on juicy text, or lots of banners? How many freesites do you have floating around out there in porn-land?
Maybe it's just the sites/sponsors you are promoting?
I've found that some sponsors just don't seem to do well on freesites, but will convert nicely with TGP traffic.
Once a month I check which sites have been converting best for me and focus more on that sponsor for my future building.
I've found that doing this makes a big difference once you've filtered out sites that, for whatever strange reasons, don't convert or suddenly stop converting.