This is a unique technique which utilizes smart targeting in who you will follow.
It is very simple as well, we are merely looking for users who are "desperate" to get a new follower and will be more appreciative when they get one (you). In return they will follow you back.
We do this by gauging their following to followers ratio, if the user is following more people than they have followers. They are a good candidate to follow, they are much more likely to appreciate you following them and they will follow you back most likely.
It's as simple as that! But very rewarding. It is worth it to focus your following efforts on users who will follow you back. Since Instagram won't let you follow unlimited people everyday, using this technique you can really improve your follow-back ratio and ensure you are efficiently utilizing every follow possible.
I have created a video demonstrating the methodology of the technique.
And here is the shell script shown in the video which crawls the profile data and calculates the ratio score_users.sh