This drill will help you get the club face and orientation of the golf club in the correct positions in the downswing to help you stop slicing and hit draws.
Make a normal backswing and the start your downswing. When the club is halfway down (parallel to the ground) take a look to make sure the club head is behind your hands (club head behind heels is ok too) and then look at your lead wrist and club face. For a right handed player, take your lead wrist and point the knuckles to the ground (bowing or adding flexion to lead wrist). This should get you club face into a position to now allow you to move your swing direction in to out to allow you to stop slicing and hit draws.