Many moons ago I shot ISU pistol competitively – not with great success I might add. I think some of what I learned there has helped my BP shooting.
Proper stance is very important. I try to take the most rigid and stable stance I can. For offhand, that generally means left elbow pointing to 6:00 against my body and right elbow pointing to 3:00. I think that tends to lock the gun in from two directions.
Make sure you are pointed in the right direction and are holding the gun correctly. Close your eyes, bring the gun to shoulder and open your eyes. If you are pointing to the left or right, adjust your feet accordingly. I won't get into proper foot position, but be consistent. If the gun is canted or the front sight is high or low, adjust your grip, shoulder or cheek position to whatever extent possible. Twisting your body to compensate will negatively affect your score.
Control your breathing. Take a good breath and let it out. Take another breath, let it half way out, hold your breath and complete the shot. The longer you try to stay on target, the more you are likely to drift about. Better to lower the gun, take a breath and try again. Control that muzzle! I once had a competitor discharge a 38 into the concrete floor directly between us.
As I recall, my Day's shooting went completely to pot after that!
Trigger control and follow through. Gradually and smoothly increase pressure on the trigger with the tip of your finger. You should not know exactly when the gun will go off. After the shot, you should still be on target – that's follow through.
And finally, go through the same routine each time – that's consistency.
As an interesting side note, the better shots I have competed against avoided caffeinated products like the plague.
Just my opinion
Now, if I could just remember some of that when I am on the line.
Laurie