There are several reputable breeders in your area. Get out to some of the shows and chat with a few of them. Find someone who is knowledgable about the breed and that is willing to advise you. If you have a girl you are breeding and you aren't getting what you'd like it may be time to move her along. You need to find a mentor that will teach you. Breeding yorkies isn't easy and producing show quality pups is even more difficult, just when you think you have moved forward something happens..so stick in there. My family thinks i am nuts, but I have some nice dogs and have had to move along a few as well. Now after 10 years of breeding, i am producing more consistant quality pups.
Check out the ytca.org site and look up some of the breeders near you and contact them. Maybe you could meet up with them at a show or two and see their dogs. Offer to assist and give a hand, they can teach you so much. If they dont' need help, pack a lunch and bring it. Let them know you want to learn and that you are there to gain knowledge.
You won't breed top winning yorkies overnight but once you have one out there that does well you will be so proud.
Duncanmom