Let’s start with balance, the basis of everything. If you move back on your heels or forward on your toes during the swing, your hands and body will try to compensate in some way to get the club head to the ball. That will change all kinds of things in your swing for the worse. You can’t fix any other swing flaw until you swing in balance. When you want to improve, you need to start by doing something harder than your desired end result. Swinging a club while standing on the foam log is a lot harder than swinging with your feet on the ground. If you can keep in balance on the log, you can do it on the ground.
Every player I’ve ever taught has asked me how to get more consistent results from their swing. One key is to work on a one-piece takeaway. We want the hands and body to work in sync. You don’t want to be too hands-oriented because then you underuse your body, don’t get as much power, and you have less control of the club. You want to start moving the club with your shoulders or your chest, not your hands. Hands players do not produce power and they do not produce consistency.