Are you looking to purchase a puppy from a breeder or adopt from a shelter? Is your intention to get a puppy for a pet, or do you intend on showing this animal?
If you are looking to purchase a puppy from a breeder, I HIGHLY recommend doing tons of research and going with an AKC registered breeder. Not to mention, you need to know EVERYTHING about the breeder from how they raise the puppies, to the puppies' environment, to seeing the parents, when and how they wean the puppies from the parents, diet, and all that good stuff. Also, read up on temperament testing, it will help get you the puppy that is right for you.
Check this link out for a head start on breeders if you are looking to purchase a puppy instead of adopting: www.akc.org/classified
Temperament/Aptitude Testing info: www.volhard.com/pages/pat.php