The best advice that I can give you is to visit first......don't leave deposits on cute photo's of pups, don't fall for anyone arranging to have pups delivered or meet you half way up a motorway, make sure that you always
see the dam with her pups, and you
see where the pups are living, anyone bringing pups into a room with no other dogs around, not good, don't swallow all the essays of how lovely mummy and daddy are, you want and need to read in any advertisements what the hip scores are, eyes, and anything else breed related is health tested, usually a sign straight away of a puppy farmer or pet breeder if there are no health tests done.
Do not confuse KC registered, (tick) with the cheeky and misleading kennel registered or DL reg.
Without papers or with - at an extra £100 charge (tut tut) is usually a sign,
We have plenty of good breeders on this site also, checked as well as possible, word of mouth is always good too.
Just a few things off the top of my head, sure others will be along with things I've forgotten,

Welcome to the site and enjoy, have much fun looking for your pup.