Well, you can ask around here. There is a breeder section -- however, it's open to almost everybody and there's no guaranty that the breeder is reputable. You can look at the list of breeders in your local YTCA chapter.
Best bet is to really take time and educate yourself on the breed & breeder. Call the breeders & talk to them at length. Ask about all their "policies." Ask about the testing they do on their pups/sires/dams. Visit breeder's homes if possible.
You have to know what you're looking for in a puppy too. Learn as much as you can about the breed. There's TONS of info online and some people here have recommended "Yorkies for Dummies" (not saying that you're a dummy, of course.)
If you have any questions about a particular breeder, you can ask here. Do google searches to find complaints or rip-off reports.
Remember, if your gut tells you that something's not right, then it probably isn't right.
Good luck. Part of the most fun is the actual search for the right puppy! He/she is out there.
