Practice swinging with your front foot turned out almost to the target which will stop you from shifting your weight to your front foot on the backswing
Put a plastic ball between your knees in order to take your backswing with your torso rotating more than your hips, disassociating the lower body from the upper body and creating more power in your swing
The easiest way to reshape your golf swing is by using a pole, stick it in the ground and make sure that your swing goes up and down the pole on the same path and just like that you will hit it straight