there are a lot of variations to Good Mornings.
You can do them with a somewhat limted ROM and go heavier, or you can go down to where you torso is almost parallel to the ground.
You can also do a more stiff leg good morning, or you can bend your knees some in the bottom for a little more hamstring emphasis. You have to be careful not to bend too much when doing this and turn it into a crappy half squat.
You can also do concentric good mornings off of the pins (or chains) in a power rack set at a particular height.
Don't round your back, and start out light.