I used ChampDogs to find our breeder. You should expect to have to contact a few, and try to get on a waiting list. Good breeders will usually want to meet you and ask lots of questions about your lifestyle, house, family etc before accepting you on to a waiting list for an upcoming mating. No genuinely good, caring breeder will just hand over a puppy to whoever turns up with the cash.
Look for health test results - not just a vet check, but the relevant genetic/DNA testing for inheritable conditions in that breed. Just because you want a pet dog rather than a show dog doesn't mean these tests should be skipped. Show breeders are often more likely to have done testing than someone just breeding from their pet.
There should be a contract, which will usually include the puppy being returned to the breeder if for any reason, at any time, you are no longer able to look after it - this is for the lifetime of the dog.
You should definitely be able to meet the dam, possibly the sire unless he is a stud dog from elsewhere, but you should have his KC details to check up on his health tests. No good breeder will mind you asking lots of questions!
Ours is our first puppy from a breeder (always had rescues before) and to be honest, the difference really showed, she is so well balanced, happy, confident, and I put that down to her excellent breeder and the hard work she put into the litter in those first 8 weeks before we got her (handling, grooming, exposure to lots of different noises and experiences etc), and in her knowledge of the lines she was breeding from. We had daily photos and videos starting before they were even born!