I am often asked how to teach a retrieve.
I train a "structured" retrieve. That is neither a forced retrieve nor a play based retrieve.
In a structured retrieve, the retrieve is taught in a systematic manner. This is the same process that is used for most forced retrieves. The difference is that rather than punishing a dog for dropping or failing to take the object, I click and reward for performing correctly, and mistakes are simply ignored.
The other major difference is that I teach the hold portion of the retrieve at the very end, after the dog understands to pick up objects and place them in my hand.
A while ago I taped a Border Collie's lessons on the shaped retrieve. The following videos were taken over five days; there was no practice or work in between sessions. As you watch, you can see that the owner and I trade off teaching - this is both to help the owner refine her technique, and also to demonstrate that different appraoches can be used to get the results.
Each dog is a unique individual and should be taught at their pace and with their temperament in mind. A clicker savvy dog will progress faster than a dog that has had mostly lure or correction based training. Don't worry about following this exact progression; simply use it as a guide to help you work through whatever challenges you may encounter.