關於愛，我是個小學生。

as hogan said, always initiate the downswing from your lower body, your right leg, pushing leftward to generate your left shoulder and right elbow, which bring your right wrist into the correct releasing or hinging position to make the club swing with greatest velosity. 

to do this, namely, to achieve greatest clubhead speed squarely, you will want to generate three sources of powers: torso rotation, elbow straightening, and wrist hinge. the faster the torso rotates, the faster the elbow straightens itself, and the faster the wrist releases downward, the faster the clubhead will pass through the ball. 

how to make the torso rotate faster? with lattisimus plus right leg's side kick. the left hip back is merely a passive must-be-so.
how to enhance the elbow straightening? to a right-hander, hold your right shoulder and let the right arm 'eject out' as  fast as possible by exerting the tricepts to contract more keenly. 
how to speed up the wrist hurl or hinge? no, we cannot, only to facilitate the tricepts to get the hard-cocked wriste push down naturally and release as it does.

to keep the trace correct, after initiating your lower body within a T-shaped move with your left hip and right elbow, mind only that of both hands straightening and ejecting out from the passive and latent right shoulder point downward to in front of the ball, and the rest will all take care of themselves and be where they're supposed to be, which is, shifting and falling both hands down with the traction of hip and elbow to a socket near the right waist, and from the very spot straightening the right elbow but hold the wrist cocked as long as you possilbly could, and seemingly brushing slightly through the right pocket, pointing downward to a couple of inches in front of the ball. and the moves of hands and shoulders form themselves into a shape of Y, which is the origin of the swing's name proper.