Those are 3 super-important points you made here, @ray4u. I've been learning from people I follow on Instagram how they get 10,000-150,000+ followers, and the 3 things you mentioned here are also talked about by them.

I would add "visibility" to the list. There are certain peak times to post on IG (I'm not sure what they are here) to get the most impressions. Other ways to enhance visibility include using tags efficiently, linking your posts to your other social media accounts, and using the different options here such as Dtube, Steemshot, Dlive, Steemit Chat, and of course Discord channels like our mutual favorite, Steemitbloggers. Best of luck to you!