"Pistol-shooting-chart (Training aid)- How I found out I was tightening my grip while pulling the trigger. Tight groups but always pulled that direction. After using the chart, I could feel what I was doing and corrected it!" this is helpful!
How to Cure Common Shooting Mistakes: There are several ways to enhance trigger control. One good exercise is the penny drill. You should be able to dry fire a handgun with a penny on the front sight and not have the penny fall off.