After you have looked at the physical attributes of each pup - size, sex, etc. - you have to look at the pup's temperament. Like the other posts have said, look for a puppy that is sociable with both you and other dogs, a puppy that is friendly and playful and not scared or timid. To check if the pup has a generally good temperament, start tickle and stroking the puppy. Move your hand over to a side while still tickling. If the pup starts to lie down and turn on its side, the pup has a good temperament. These pups are easy to train and very eager to please.
Good luck. We are so excited for you!!