If you can, achieve a decent position at the top of your backswing (i.e., good posture, square clubface). The transition into the downswing requires the hands and arms move last. This means the rest of your body will initiate the transition from backswing to downswing.
Many golfers fire their hands and/or arms to initiate the downswing. This moves the club off plane and off path. It seems reasonable that we would use our hands and arms to move the club back to the impact zone. But how we do this can have a huge affect on your ball striking.
Some doctrines suggest that a downswing transition sequence starts from the ground up: feet, knees, hips, upper torso, arms and finally the wrist and hands release or unhinge through the impact zone.
Take swinging a hammer for instance – you load it into position (backswing) and as you transition with the downswing what is your first movement? Do you move your wrist first? No, you let your wrist unhinge on its own, holding the hammer, but not forcibly moving your wrist to make contact.
Think about throwing a frisbee. You swing or load your arm across your chest, turn your body back and your first move to throw it is a step, then turning your body toward the target flinging your arm and allowing your hand/wrist to release naturally. If you force the throw, making your first move your hand or arm, you will loose both speed and accuracy. This is a similar mistake golfers make when swinging a club.
Try this with a frisbee to get a sense of sequence. You will notice that the first move in the transition is a step toward your target.
Transition = feet (step) – hips – upper torso – arm – wrist. One-handed swings or using a swing tool (Swing Whip) can give you a sense of the proper transition.
Breaking your current sequence can be difficult and will take consistent effort. However, understanding what you are trying to achieve is the first step in the right direction.