I observed a group of young girls playing golf this past week. I was so impressed with their care of the green. They laid the flag down very carefully out of the way of play. Have you ever looked at the groove that a flagstick makes on the green when dropped from full height? They fixed their ballmarks. They walked around the lines of others’ putts and were conscious of others’ lines when tapping in a putt.
A negative habit I’ve observed on occasion is that of scooping the ball out of the hole with the head of the putter. There’s too much potential for damage to the cup when doing this.
Good etiquette is simply being considerate of the course and other players.