Train to develop muscle memory
It's a sub conscious thing that I'm not even aware of sometimes. Friends at the range will tell me and I won't even realize.
Suggestion:
Clear your handgun, visually and physically inspect to ensure it's unloaded, and leave your ammo in another room.
Then, with your cleared and unloaded pistol, dedicate a certain amount of time to training. You can draw from a holster for additional reps in drawing from a holster if you feel the need, but to "train your trigger finger" you can simply go back and forth from the high ready - muzzle pointed at target but arms lowering the gun down to about low-chest level - with finger OFF trigger and up along the frame of the gun.
Then "punch" to a presentation of the gun, while moving your finger down onto the trigger - without pressure or squeezing.
Lower to high-ready and finger comes back off the trigger.
'Lather, rinse and repeat' this up and down exercise a couple dozens times a session. Don't beat yourself up if you catch your finger dragging on the trigger at the high-ready - just so long as you catch yourself and correct yourself. Positive reinforcement with numerous correct repitions, done over a period of time, and you will develop muscle memory.
You don't have to grow up with a gun in your hand to develop muscle memory, just like learning to drive a stick didn't come at age 5 (for most of us). When you first learn to drive a stick, all your focus is on NOT screwing up, lurching and stalling and all the many things you have to do simulataneously. Now, looking back, you drive a stick while drinking coffee and finding your favorite CD and don't even think about shifting. You just do it and usually without issue.
Training your trigger finger to be your best, safest buddy is the same. Train with a purpose and goal in mind, and you will get there.
Don't be like the DEA agent who was the only one in the room 'professional enough' to shoot himself in the foot, even after "clearing" the "Glock 40." Nobody wants to train with THAT guy. :secret: