Over the years of playing and teaching I have found that the game of golf always comes back to fundamentals. These fundamentals include grip, alignment, posture, rhythm and balance. When a player has good fundamentals it will set up for successes in the golf swing. So when I teach I always start with the basics, then move on from there using teaching aids and trackman to identify patterns and tendencies in swings. Even with PGA tour player Ryan Moore, who is a 5 time champion, we always start our work by making sure his fundamentals are where they need to be.
Drills are my favorite way of helping a player improve there game. Making changes in golf are hard so having a way of knowing what you are doing is helping without trying to.