I tried Healzer's suggested like, follow, comment, repin, and pin actions and they do yield a very nice percentage of followers back. I did his action across 14 accounts. the biggest challange is just the workflow in pinblaster to build the right type of targeted user list to do all the actions. Pinning of course is the easiest since you just scrape other peoples built out boards. But getting a good spread of users pins to like, comment, and repin is really challenging since as are looking at about another 1500 pins actions.