This is a text from an American breeder, which I show to those who look for me wanting dogs for breeding, that's why I don't sell dogs for breeding, the puppies are sold only for company, without reproductive guarantees.

It is not easy to become a responsible and respected breeder.

Most of the respected and responsible breeders I know (myself included) became breeders after being involved in the sport of purebred dogs in one way or another. This can be by participating in dog shows, obedience, agility or hunting. This involvement brought great interest in the breed, a small step in learning what makes a Golden Retriever a good specimen of the breed, and a desire to contribute and create better dogs. You will learn  watching a dog interact with the person (sometimes he had learned not-so-good things). You will start by understanding the particular genetic traits of the breed (every dog has good and bad genetic traits too, unfortunately) and you will start  to prioritize and understand what you would like to produce in your creative program. You will study pedigrees and know the main bloodlines well. This takes time I've been raising for 5 years and I still can't guarantee a perfect puppy.

Breeding dogs is not a good way to make money, as many think. First you need to acquire a quality dog, and this will cost you between R$3500 and R$5000, then you raise and train the puppy (it can cost you around R$4000), then you participate in competitions (it can cost R$10,000 per championship, but that depends a lot on the dog you have and where you compete with it). And then I need to do the health tests (coxofemoral dysplasia, elbows, eyes and heart) with new genetic tests of Pra1, pra2 and pra (prcd) emerging in the breed now. Now if you have a female doing well so far in all areas there is still the possibility that she will fail a health check at 2 years old,  and then you go back to step one, choosing a new puppy and starting all over again. I personally didn't have an excellent breeding female until my third attempt. If the initials BOB, SAS, BIS, PRA, CHD, CERF, OFA, BWA mean nothing to you, it means you still have a LOT to learn about the breed. This takes quite a while.

You breed dogs and it's really expensive. Tests like vaginal cytology, progesterone, vaginoscopy, inseminations will cost you per  around R$1500.00, not to mention that you will need to have a well-defined space, maternity box, recreation area, socialization of puppies. And there may still be other veterinary costs, if you need to take your dog to the vet to save mom and babies in the middle of the night, be prepared to spend around R$3000.00, and that if your female gets pregnant, because if If you don't, you'll have to wait another 8 months and do it all over again. Add the knowledge you'll need to raise a healthy litter, food, vaccines, supplements, etc. You will need to be at home 24/7 for at least 30 days to assist in the development of the litter. This is where joining the national and world clubs of the breed comes in handy, and of course there are debts and expectations regarding your work in these clubs.

This could be more information than you expected, or not enough. Raising beautiful, healthy dogs is not for the faint of heart.