When I shoot my revolver, I will load empty shells in a couple random spots, spin it, and close it. This immediately exposes any flinching or anticipating I'm doing. I squeeze the trigger, the gun moves slightly downward and no round is fired.

Do that a couple times and you learn to remain neutral pretty quick.

It's not as easy on a magazine-loaded pistol. I imagine you'd need to get some purpose-made dead rounds. And the randomization is harder.