Not much you can do to tweek Perk. Run 5 phones per acct and run them as close to 24/7 as you can. The App trailers are the shortest, so you'll get more pts by restarting to them more often. Aim for restarting very 2 hrs. Every week or two you should reset your phones or at least delete the app data. This will reduce the loading times for the videos.
Doing these things, you should be around at least $1/phone/day.