OP, two items I can offer. One, do not over caffeinate on range days...
Most important, when you shoot, make sure your shooting hand is relaxed. This may mean making sure your entire forearm in your shooting hand is relaxed...There are various views on how to grip a gun, some of the "proes" say as hard as you can, some quote the 70/30 rule, some say almost all the holding force comes from the support hand and the trigger hand is very relaxed. We are all different, so you will need to try it out and find what works for you....For me "the hard as you can option" doesn't work at all (outside a really close-up string). I was in the 70/30 camp and doing fine, but I've been working on this recently and realized for me it is about 90% support hand/10% trigger hand for optimal results. With the trigger side forearm and hand relaxed, you are very, very, much more likely (not) to flinch (or move the gun), and have a perfect trigger pull. (Please understand, if you shoot enough rounds, like many hundreds, fatigue will set in, and it is very hard to not flinch. Best to stop before this happens).
Give it a try, at first you will need to concentrate on this, later it will be "muscle-memory".
C.A.
All the other suggestions above are good too from the other Guys, everything adds-up in your training.