The only tip worth knowing about breeders is fuck those guys right in their ears. Do your soul a favor and adopt - you can definitely find one of those in a shelter around your parts, I guarantee it, and while it may not be "purebred"

it will still be cool, it will love you forever for saving it from being miserable/put to sleep, and will cost you WAAAAAAAAAY less money (breeders will charge thousands for "purebreds", shelters may charge a few hundred, tops). Seriously, even if you can't find one, wait a little while, and one will turn up.
My uncle went to a breeder for his dog, and it turned out to be inbred and now has crazy seizures all of the time - there's no way to tell about that kind of stuff unless it's blatantly obvious (in which case a breeder won't even let a dog like that live) or unless you take it to a vet after purchase, in which case it's too late.
Look in the shelters first, you'll be happy you did after you see how happy your new friend is to be out of the slam and in with a good home.