By summer, most golfers have spent months seeing their drives go right. They react by twisting their upper bodies to the left at address. I'll start it left, and give it room to turn. But that twisted position only makes you cut across the ball—and exaggerates your slice.
If this cycle sounds familiar, you have to be disciplined about your setup. Forget about what you've been seeing. With the ball opposite your front heel, set your left shoulder higher than your right, and your right arm lower than your left arm. You should feel a little closed to the target.
From there, sweep the club back and swing it over your right shoulder. Coming down, keep it on an inside path. Extend and rotate your arms as you strike the inside part of the ball. This will help you hit up slightly (slicers tend to hit down). Get it right, and avoid that summer driving slump.