One of the requirements I have of people who take one of my puppies is to attend puppy classes. The age from 8-16 weeks is a unique window to influence your puppy for the rest of its life. Lessons learned (bad and good) at this time well be "cooked" into your adult dog. All of our puppies have unique temperaments (just like people) and this is the time the pup learns to cope in world with its given temperament.
I urge you to download and review Avidog's "97 Ways to Create Great Puppies!" Its free!