There are many excellent books and DVDs out there by well renowned trainers with clinical training in the science of behavior. Anyone can call themselves a trainer (no training or certification required), so I always recommend going to someone who truly has training and certification in the science of behavior. We are still living with a lot of myth about canine behavior that gets perpetuated by many "trainers".
An excellent trainer AND communicator (always a plus) is Patricia McConnell - I highly recommend "The Other End of the Leash" but all of her books and videos are excellent.
http://www.dogsbestfriendtraining.com She also has a great Puppy book, a Puppy Primer, with very basic obedience instruction (sit, stay, and come)
Also, The Culture Clash by Jean Donaldson is excellent, but a tougher read.
Turid Rugaas' On Talking Terms with Dogs is also a must have:
http://www.canis.no/rugaas/books.phpThis is where I would start and I would go to:
The Animal Behavior Society
http://www.animalbehavior.orgto find a qualified trainer in my area - NOT the AKC who is a "sporting registry" and does not qualify the breeders or trainers it may list.