I usually go with accounts that have more than 50k followers but less than 1 million. For example, my automated one is in politics. I usually search for big political figures that are in my niche, go through their following, follow/unfollow and like their pictures. I set up FL to do that. Comments I do manually in both automated and manual profiles. I think of a genuine comment that relates to their picture, not the typical BS "Nice pic" comment.
To be honest, you have to be interactive in order to get a decent followback rates. I have noticed that the last few days of my weeks and today I just passed 1,000 followers!!
You can do it. Be persistent, do the methods, be interactive with your followers, and you'll see your numbers increase