An insult from a woman helped me.
The best tip I ever got to improve with a handgun was an insult from a female handgun instructor. She told me I had wimpy limp wrists---I was a body builder at the time and a towering physical hulk. She prescribed finger and wrist exercises with a squeeze grip exerciser and a chain roll to develop strength in my fingers and wrists. The chain roll is a common gym exercise and uses a 1 inch dowel with a thin 3-4 foot chain attached and a 10 lb weight disk attached to the chain. Roll it up slowly, roll it down slowly in repetitions of 20. Get your hands and wrists powerfully strong and holding a handgun steady while squeezing the trigger smoothly will be a LOT easier.