It can't be stressed enough: You can't overdo socialization and training when your pug is a puppy. Many behavior problems will never develop — or can be easily solved — if your pug learns early in life that you are in charge, that there are all kinds of interesting sights, sounds, and people in the world, and that doing what you ask always leads to good things. Take your pug to puppy kindergarten, let him run errands with you (as long as you never have to leave him in a hot car), sign him up for basic obedience training after puppy kindergarten, and make friends with other pug owners so you can set up regular play dates. Your pug is happy when you're happy, but he needs your guidance to show him how to make that happen.