Shoot more, pay attention to the good shooters you see . . .
As stated, quite well, the relation of the bore axis to the hand is a factor, i.e. how high the weapon is held in the hand, and the grip, stance, presentation to the target intended. The best way to become a better shooter is to attend some formal instruction. I have been to Frontsight and Mike is a Gunsite guy. I went to the Federal Law Enforcement Training Center in Brunswick, Georgia and was taught by FBI, SS, US Marshall, and military instructors as well. At the S.O. we have a pretty awesome clearing house range that we shoot to qualify in all conditions. Check and see if you have a local IDPA chapter, try them on the web. That's a fun shoot. Work every evening with a grip builder as well and make sure that you divorce the movement of your trigger finger from the remainder of your hand. Most shooters I see shooting vertically displaced strings are "squeezing" with their whole hand or jerking the trigger in anticipation of recoil. Dry fire practice as well, carefully with no ammo anywhere available. I use snap caps, some don't. Have fun, keep an open mind and shoot, shoot, shoot!