I agree with the YTCA, at
www.ytca.org as a good start breeder referral. However, I would still urge you to make sure you interview any breeder and be sure of what you are hearing. YTCA has a code of ethics that the members must agree to before joining. BUt there is a disclaimer that the Club will not be held responsible if something goes wrong and you aren't happy with the breeder on their referral.
As a bit of a checklist of a good breeder you should be looking for someone who is only selling the puppy under limited registration not allowing any breeding. It will be AKC registered and no less than 12 weeks of age. It will not be called teacup etc, you can read that bit on the YTCA site. They should be able to show you the mother and other relatives of your puppy. You want to see some of the adults as that is pretty much what your puppy will grow up to look like.
There should be guarantees and genetic guarantees for at least a couple of years. They should be very knowledgable of the breed and be imparting all kinds of information about your puppy, its care, what to avoid that sort of thing. In my contract, I also require the puppy to be returned to me anytime in its lifetime should the buyer not be able to keep it for any reason. The initial sale, when I agree to sell one to a buyer, is on a trial basis. The buyer can return it to me anytime within that first month with a full refund if it isn't working out for them. I also have genetic guarantees of 5 years, other health guarantees of one year. I also advise them of Vets in their area that are good with toy breeds.
The breeder should only be selling their own puppies. They may refer you to another breeder friend if they don't have anything for sale but knows someone who does.
They should be asking you many questions about who else will be living with this puppy, how much you are home, advise about housebreaking, what to watch for in a young pup if they are getting into hypoglycemia problems and they should be willing to answer your questions.
Hope this helps a bit.