If you're not happy with the followback ratio, then change the targeting. If you're following some huge account's followers, you find some other account which has huge teen following. Check the followback ratio again and if it's still not good, find some other source. I am getting 20% FB ratio in one of my accounts. I haven't started my journey yet, but I had 5 accounts which I put on warm up for quite some time now. Add me on skype, maybe we can learn a thing or two from each other.