For me, my standard is to make sure that I turn my shoulder under my chin and make sure that I feel like I am taking a 3/4 swing with a firm right wrist. My tendency has been to overswing a ton so by thinking 3/4, I am making a swing that is pretty far back. I also keep my wrist firm to prevent it from breaking down at the top. From there, I just focus on a good transition keeping my head under control and behind the ball.