First of all an accredited breeder. Then you can be more than reasonably sure of the pup's "credentials". Also you will have a signed agreement, if the puppy is not what you were expecting/ you find in later years you can't keep him, the breeder will have him back (in not what you were expecting, the breeder cannot guarantee success in the show ring!) But they will have him back.
Always insist on meeting the mother and reassuring yourself that she is healthy and friendly and, if possible the father, or, at least, find out about him and make sure of his temperament.
Poodles are sweet dogs, very intelligent, full of fun and need plenty of occupation, rather like a border collie.
Good luck in your search
