Improve your upper body strength with some free weight training. Articulating 10 to 15 pound dumbbells provides the arm and shoulder strength necessary for good pistol shooting.
Increase your hearing protection NRR.
Get your eyes examined for acuity at your handgun front sight distance. Get corrective lens shooting glasses accordingly.
Don't waste your time and ammunition going shooting if you did not get a good night's sleep the night before.
Shoot on an outdoor range, well away from rifle shooters.
Buy an
Advantage Arms .22lr conversion kit for your Glock and use it for 50 rounds or so at the outset of each range session to focus on trigger manipulation.
Conclude each range session with 10 to 20 rounds of .22lr through the conversion unit to assess your status.
Shoot five round strings, not full magazines, until you are satisfied with your trigger manipulation. The more frequent breaks give you a chance to calm down and assess your progress.
Practice some single handed shooting, interspersed among the typical two handed shooting strings. Poor single handed shooting often indicates weak upper body strength.