Puppies and More...
Find a Reputable Breeder
Reputable breeders only produce a litter with the goal of improving their breed and with the full intent of keeping a puppy from the litter with which to continue their efforts.  They do not breed to make money, to supply the pet market during a wave of breed popularity, to give the kids a sex education, or simply because they happen to have two dogs of the same breed on the premises. These last are all spurious reasons to add more dogs to the current population.  If the breeder has produced a litter for a silly reason, beware!

Reputable breeders nearly always belong to a local or national breed club and they actively compete with their dogs.  Competitions include licensed dog shows, field trials, obedience trials, herding trials, tracking events, earth dog trials and sled dog racing (among others).  Reputable breeders know that AKC registration alone does not confer or imply quality or breeding value, any more than a DMV registration means you have a top quality car.  Competition with other well-bred dogs helps to gauge whether a given dog is worthy of being bred; whether it offers its breed virtues that are worth reproducing.  If the breeder does not belong to any dog organizations or compete with their dogs, beware!
Reputable breeders are willing and eager to spend time with you, explaining, teaching and advising you about their breed.  They will make the disadvantages of owning their breed crystal clear, and it may be the first topic of conversation!  No breed is perfect for everyone, and the responsible breeder wants to be absolutely sure that you really want, and are prepared to care for, this kind of dog for the life of the dog, not just during the "cute puppy stage".  If the breeder does not go into breed peculiarities, beware!

Reputable breeders will screen you carefully, to assure your suitability for owning their breed.  They will not sell a large, active dog to someone without a fence, for example, nor a tiny toy dog to a home with small children.  It is cruel to place a dog in an unsuitable home, and unethical to strap people with an unsuitable dog.  A reputable breeder will refuse a sale, regardless of any personal financial strain or the amount of work involved, rather than place any dog in an unworkable situation.  If the breeder does not question you closely about your home, your family, and your expectations of the dog, beware!

Reputable breeders sell only healthy stock, fully vetted, and guaranteed for some reasonable length of time after the sale.  Their dogs are tested for any genetic deficiencies which can be detected by the age at which the dog is sold.  Puppies should never be offered for sale any younger than 7 weeks of age, and preferably 8 weeks.  If they are, you may be sure they have not had all their shots.  Adult dogs offered for sale should be completely up to date on shots, recently wormed and heartworm-tested.  Records of all veterinary treatments and testing should be offered to you in writing.  If vaccinations are not complete and up to date, breed-appropriate testing for genetic defects hasn't been done (or the breeder says "Oh, that's not a problem in this breed" when you know it is), puppies are offered for sale at an extremely young age, or the breeder's dogs appear unwell, beware!