This is really awesome. I have used a similar strategy to grow followers in the parenting niche on Pinterest, and I plan to try your recommendations on Instagram. Your point about monitoring your feed is a good one — once it fills with junk you’ve gone wrong. I also find it useful to immediately interact with someone who likes/shares my stuff — tends to encourage them to do more of it.
Question: Do you eventually unfollow some people? I worry about having too many people that I follow, and looking like a spammer.