I don't have any experience with Pinterest. I've shared a few articles on LinkedIn, but I couldn't really tell if it made a difference or not.

I was in FB groups a long time ago and it's mostly a waste of time.

My best tip would be just to find people you enjoy reading and leave genuine comments. Over time, you will make friends and they will support you.

Earning money or getting reads on Medium is not easy in the beginning. It often takes a few months to get established.