Buying from a registered and reputable breeder is the responsible thing to do. You can be sure that you are buying a happy pup in good health that has been well cared for. Conduct a fair amount of research before deciding on a breeder.
It would be best if you only bought from breeders who follow the guidelines set out by the RSPCA and are correctly registered. Many breeders pose as being ethical, while they are actually puppy mills, so a considerable amount of research is necessary.
It is always a good idea to contact the proper authorities so that you can verify your chosen breeder. Do not trust Facebook, ads, or any random online platform; always look deeper into the breeder's history, and do your homework!