Water Work

Get your dog used to wearing a canine life jacket.  Make sure the one you select fits your dog properly, offers good support and floatation and is adjusted comfortably.  If your dog is not a big fan of his new apparel, work to change his attitude by giving good treats when putting on the jacket, having him wear his jacket at meal times (for eager eaters) and playing fun games while he wears his jacket.  A life jacket can make newbie swimmers more confident and allow confident swimmers to focus more on brain work rather than staying afloat when learning new skills in the water

Try to develop a good play retrieve on land first.  Bringing a retrieving toy to the water with you can keep your dog focused on swimming and sticking with you and not running amok and disturbing others.  Chose a floating toy that you only play with interactively with your dog and put it away when you are not training with it so it has a high value for the dog.  Once your dog is excited about his toy and play retrieves in a low distraction environment, gradually take your game to an area where there is more distraction (in my house we move from indoors, to back patio/concrete, to back lawn (good smells in the grass) to the front of the house (cars passing by, neighbors gardening, people walking dogs).  After that, we might take the behavior “on the road” to the nearest park (with the pup on a long line for safety).

You can also “shape” a more formal retrieve, and this is highly recommended if you want to pursue titles that involve retrieving skills (like water trials or obedience).  A a Guide to the Inducive Retrieve by Sue Sternberg provides simple instructions for "shaping" a reliable retrieve using food rewards.