The useual, go to a KC registered breeder.Ask for hip/eye scores, see both parents if possable and be prepared to walk away if you dont feel right about the breeder.
Good luck!
Can't KC reg a JRT I thought? As in not recognised breed that comes with papers? Probably wrong!
Try see botht he parents, see what their temperments are like. When picking your puppy, nice alert friendly one, check for nice clear eyes, no abnormal bits on body etc
No you're right, a JRT isn't KC registerable, there is a Jack Russell Terrier Club of Great Britain who specialise in the traditional shorter legged JRT.
Echo others & see parents - at least mum. Make sure the breeder knows about what they've weaned the pup onto and what they've wormed it with.
Most breeders will also provide you with an information pack, includes info about parents, worming, vaccines/vet checks and a lot of people state that if ever you have a problem, no matter what they'll take pup back be it 12wks, 12mnth, 12yr - even if you don't invisage there being a problem it also shows the breeder cares. They should always be there for continual support after all they brought pup into the world.
The KC registered breed is the Parson Jack Russell. Much longer legs and not nearly as cute as JRT imo. Don't think you will find many hip scored Jack Russells, not sure about eyes. Main think is to make sure you see the mother and that she is in good condition and friendly. Wouldn't be quite so concerned is father is not on premises, some breeders use other peoples stud dogs, but breeder should be happy to tell you where dog is and give you option to go and see him. Pups should be in clean surroundings, well fed and lively, and of course friendly. I think you usually get a feeling about whether or not a breeder is genuine. Good luck.