I would say the best way is through careful social observation. Put yourself in many different types of situations and observe the unspoken "rules" around mann

I would say the best way is through careful social observation. Put yourself in many different types of situations and observe the unspoken "rules" around mannerisms. Try and eat at different restaurants, attend a ball game, go to the opera, join a meetup -- each one of these different scenarios will help you learn and grow.