I posted this before, so here goes. Professionals? Not everyone has access to pros and if they charge a fee, can you afford it along with lots of practice rounds?
Years ago I had 2 consistent shooting partners. We devised a plan to improve our long range accuracy. When shooting revolvers, we would let someone else load our pistol. This meant you may have 1, 2, 3, 4, 5, 6, or no rounds in the cylinder, in any random order. You can do this on your own by loading some dummy rounds and mixing them with your good rounds. You never know what your hammer will drop on. Makes you really concentrate on the trigger pull, I mean really concentrate. Do this for several hundred rounds and you'll be shooting limbs out of trees, I promise.
With an auto, again load some dummy rounds and fill your mag. Same principle, you'll never know what your hammer will fall on. If you flinch, you'll know it, big time. I did this off and on for years, and the end result is marksmanship worthy of the pistol you shoot.
You will also be able to effectively critique the accuracy potential of another pistol. Trust me, this works.