Rotate the body, not the forearms, in the takeaway
The first move of the backswing is a rotational movement of the body but not of the arms: the lead arm rotates only as much as the torso rotates, so you are not independently rotating the lead arm. The speaker says a common fault is an immediate rotation of the forearms right off the bat, and that rotating the forearms at the beginning of the motion takes the club off its plane.
Channel: Todd Graves
Watch official source at 5:57