Perhaps the greatest shotmaker of all time, Byron Nelson, swung the club in such a way that his club was square to the target and moving down the target line for twelve inches after impact. Playing this way, Nelson hit it so consistently that he could play entire rounds scarcely missing a shot.
So, there you have it. The first foot going back, and the first foot going through impact are key to hitting good golf shots. The easiest way to have control over those two feet is by using your top hand. If, as a right-handed player, you push the club straight back to begin the swing using your left hand; and if you pull the club through impact straight down the target line through impact with your left hand; you won't believe how straight you can hit it.
The straightest hitter of them all, Moe Norman, said he pulled the club down the line with his left hand and felt he kept his clubface square to the target for 22 inches after impact. Whether he actually managed to do this or not is really immaterial. The fact is he felt that he was doing this. Moe also took care of the first foot of the backswing by setting his club about a foot behind the ball for full shots. By doing this he felt he couldn't take the club outside, and he couldn't snatch it to the inside going back.
If you aren't hitting the ball square, or straight, try looking to the first two feet--the first foot going back, and the first foot going through. Arnie, Moe, and Lord Byron played that way. And they knew a little something about ballstriking.