So many errors in the swing come from the upper body and the lower body not moving together in a coordinated way. If the lower body gets too far ahead on the downswing, the arms will be left behind and the clubface will come into the ball wide open. If the upper body leads, weight cannot return to the left side. Weak, off-target shots result.
Try this image to keep yourself connected throughout the swing. Imagine there is a string going from your left hip straight to your right shoulder. That it goes through your body doesn’t matter. Pretend your body is transparent to this string.
When you swing back, the right shoulder has to turn back behind you. Because the right shoulder is connected by this string to the left hip, the left hip will be pulled around, too. All the slack is out of the string.
Now on the downswing, it is the left hip that leads. As it slides and turns into the ball, it pulls the string and the right shoulder turns with along with the hip. Nothing gets left behind. Your body stays connected, and the clubface gets delivered back to the ball square and on line.
What more could you want?