My experience with successful trout C&R has been this: never handle the fish with my hands, only have them out of the water for a quick picture if I want to record/document the fish, and when I do that I hold the spinner, not the fish. Then back in the water, unhook and release. Last weekend I released 6 newly stocked trout (the most fragile of state in my opinion) with 100% success.
Of course, I kept my first two for the grill-Delicious!