This can be tough, especially when the golfer tries to practice with hard swings and a longer clubs. Let me give some ideas on how to address this. Beginning without a club, walk-through the swing and feel the changes you are trying to change. When you have a good feel of these changes, begin with a short club, easy swings and feel the changes until you can build up to the longer clubs. As you go through these changes, look at the video of the swings from time to time so you can verify that you are getting to the point you want to.
Golf can be a challenge and improving can really be a challenge.
Take it slow, be smart and you will improve, have fun doing it, don t get frustrated.