What made the dfference for me, accuracy wise, was to finally gain an understanding of the correct sight picture ........ie focus on the front sight and the target and rear sight blur.
I was an OK shot, understood trigger and sight alignment, did not flinch, but what allowed me to become some better was the focus issue. To get that, I had to be taught, at the LE academy. Nobody had explained it prior, rifle or handgun, despite shooting alot as a kid in a shooting/hunting family.
As I age, my inability to focus up front (old eyes) has begun to effect my shooting with certain barrel lengths and iron sights.