It takes some concentration and an open mind. A really open mind. I have only been able to instruct those who listen. In my line of thinking listening is doing.
You might be shooting low because of what is mentioned above. "Bucking the gun." Anticipating the recoil. If you are then you might be shooting a heavier caliber. There are good fixes posted in the prior postings.
You might be shooting low because you are dipping your head when you shoot. As stupid as it sounds people do it as a habit learned from hunkering behind a rifle IMHO.
The line of sight is critical. It begins from the shooter's eye and continues through "aligned" sights to the bull. Trust me when I tell you I have seen countless people shoot low because of hunkering their head each and every time they get ready to fire.
Bring the pistol up to your line of sight. Do not lower your eyes to the pistol's line of sight.
Focus on the front sight and not the target and let the bullet go. Do not focus on the target.
Target alignment. Place the top of the front sight where you want the bullet to go.
When shooting a pistol remember this one thing. You will be hard pressed to notice if the muzzle moves during the shot. No matter how much focus you are paying attention to the front sight.
Dry firing may not help if you are shooting low if you are having a problem with sight alignment. You need feedback.
1. Treat every firearm as if it were loaded.
2. Never point a firearm at anything you do not intend to shoot.
3. Keep the finger off the trigger and firearm on safe until ready to shoot.
4. Know the target and what's beyond it.