I would suggest reading "Water Dog" by Richard A Wolters. It's and older book but pretty much everything since is based on his techniques.

Being a pointer guy I can't help with the specifics of retrievers (hand signals and all that crap) but here's the basics.

Start today. For the next couple of months or so use only positive reinforcements. A simple pat on the head works best. If he starts fighting back or attempts that dominant stuff place him in the kennel and ignore him. Don't yell or get mad. The first few months are about establishing trust and introducing the basic commands.

Keep the training session's short but do them often. Decide on what commands you will use and the associated hand signal. Teach both from the biginning.

I'd lose the whistle. Everybody's thinks they're on ESPN now and blowing them damn things. Poor dogs running back and forth wondering which damn whistle is theirs.

I'd start with sit/stay as this gives control to the trainer. As he learns one command introduce another. This way you can end each session posativly with a command he has already mastered.

By July/Aug your pup should know all of his commands. Now start enforcing them.

Take lots of walks and field trips. This is the fun training for both of you. You can even carry a fishing pole!

Come Oct. put down the fishing pole and hunt your ass off .

Good Luck and Have Fun!!!