I think that getting mentally relaxed is the most important key to a good round. It takes time to forget about what has happened previous to arriving at the course.
With practice putts I agree that the short ones are the confidence builders that allow you to have a go at the one putt on the first hole, instead of being tentative. The first hole at my home course is a par 3 190 yards from an elevated tee. If I can walk up to the tee with positive thoughts about the hole, instead of remembering when I last blew out, then my round is ok.