One reason for Jack Nicklaus' greatness can be traced to the meticulous nature of his set up routine when he picked and focused on his intermediate target
Use a piece of string to fix your swing path by placing a ball inside or outside of the string, when you come down to hit the ball you can get a perfect visual to see if your club is traveling inside out or outside in
The roll of the right leg in the swing is very misunderstood in golf, it is extremely important for control and distance, as the club comes into impact the right knee, foot and ankle roll in and at the finish the right thigh should catch up with your left thigh