Questions About the Breeder
1). Do they regularly post photos of the litter on their website or blog?
2). Will they willingly provide references from other people who have purchased puppies and now have adult dogs (ideally those aged 3 years and older)?
They will likely not give you these until after they have had a chance to get to know you and know that you will be a good match for them and their puppy/dog. This protects their references.
Also find out who their vet is and if they have been involved in checking the puppies and parents. Ask references about health and temperament issues and other concerns you may have.
3). Do they ask for a deposit to ensure your commitment to a puppy from their litter.
4). Will have you sign a contract that agrees to all these terms and more? And they will sign it too. They will provide you with a copy.
5). Most or all puppies in the litter should be pre-sold before reaching homing age. Reputable breeders have a good reputation, people on a waiting list for puppies -often for one or two years ahead-and rarely need to advertise in the classified ads (newspaper or online) except in unusual circumstances.
6). Does the breeder have a good reputation among other breeders of similar dogs (same or similar breeder or group of dogs). Call the other breeders up and ask them about the other breeders once you have narrowed it down. Be aware though that this may be both their friends and competition so handle it accordingly. Be respectful to all involved. This is not a gossip mission, it is only to find the information you need.
7). Are open to questions from you about the above and more as well.
8). Will ask you many questions about your living situation, family and long-term plans. They want to make sure that their breed and individual dog will be the best fit possible for your situation. They are not being nosy. They are looking out for the best interests of their dog.