Hello. Welcome to YT!
I know it's hard trying to maintain patience when you are so eager to have a new little one. But taking your time to find a reputable breeder and the perfect pup for you is well worth it. Here are few things to look out for when searching for a breeder. These are some common red flags to be on the look out for and avoid.
* releasing pups at an extremely young age (reputable breeders do not place Yorkie pups until they are around 12 weeks old)
* having multiple litters in a short amount of time
* not placing pups on a s/n contract
* breeding dogs that vary greatly from the standard (which means that a good knowledge of the standard first is a must)
* not having specific health test performed on dogs and breeding stock (this means more than just "vet checked and healthy")
* a skimpy sales agreement/health guarantee that does not protect both you and the breeder, or not signed agreement at all
* breeding extremely small females (under 5 lbs)
* advertising "teacups" or "miniatures"
* breeding multiple breeds or mixing breeds for "designer dogs"
* USDA registered breeders
If anything, ask here for opinions first. Chances are, someone here will have experience with the breeder, or at the very least, can help you look for red flags you may have missed.
Good Luck!