For my game, it has been course management. I had to figure out what my distances were, and playing safer golf. Learning that I didn't have to hit driver all the time to set myself up for a good score.
Also, I worked on shaping my shots. I learned how to drawing, and fading the ball efficiently.
With putting I worked on lagging the ball better for those long putts, and for those shorter ones, I concentrated on getting the ball rolling on a set path. I tell myself that I want it to roll over this mark, and not really thinking about the mechanics of the stroke anymore, because I've gotten to the point where I have the confidence that I can make a good stroke on the ball.