The best guidelines to follow when looking for a puppy is to follow the AKC Standards or the BCA standards. Even if you are not planning on showing your pet by following the standards you will get the true look of the breed and usually a healthier dog.  The breeder you buy from is also very important.  A breeder with integrity will only breed a healthy and fit female to a healthy and fit male, which will should produce a healthy fit puppy.  A good breeder is always trying to breed to produce puppies as close to the standard as possible and to weed out health issues. You should feel comfortable with your breeder.