Proper socialization

Submit your puppy to an environment as rich as possible.

The importance of stimulation on the behavioral development of puppies is paramount:
"A puppy that grows in a place where visual stimuli, sound, touch, smell are few or always have the same failure of exploratory behavior, anxiety and inhibition-disrupting serious.

For example, consider multiply at a very young age games, meetings (with humans and other animals), places for walks (town and country), the most varied situations. Richer experiences are more serene and balanced is your dog.