Diet is important as well. Try to stay away from caffeine shortly before you are going to shoot. A great big gut bomb of a meal right before will make sitting position challenging too.
Obviously practice. Competitive small bore shooters often practice dry firing as much as live firing.
Keep records. Wind, temperature, humidity, lighting, as well as load data.
LOL!! Col. I'm not laughing at you, but that reminds me back in 1975 when they decided to forbid THE Marine Corps Rifle Team from drinking coffee before a match. OMG, the scores were HORRIBLE that day! Grin. THEN they changed it to have your normal coffee in the morning before the match, but not drink more an hour before shooting and none until after shooting. Since they changed over the relays, the guys could then drink some coffee while they were pulling targets.
Our rule of thumb was dry fire at least 10 shots for every 1 shot fired in competition. It was not unusual for our guys to dry fire 50 times a night (or more) on practice days.
I absolutely could not agree more about keeping records when firing and I would add keeping a data book on all your shots, at least in practice.
I shot Expert Rifle and Pistol every year after boot camp, BUT even though I spent as much time around the shooters on the Big Team or near them and our Scout Sniper Instructors, it took me until I went through the NRA Police Firearms Instructors Course for something to really sink in - that they had tried to teach me from boot camp onward. This was:
1. Establish your natural point of aim before EVERY round fired in Slow Fire and especially offhand. This means stand comfortably, raise your rifle and aim, close your eyes for a few seconds until it feels right, then open your eyes to see how far off target you are. Adjust your feet positions and try again while aiming. Repeat until when you open your eyes, you are in the center of the target. Then DON'T move your feet from that position as you load and fire the rest of the shots.
2. Keep Perfect Sight alignment at all times, even as the rifle naturally moves around in your arms, naturally. (This is commonly known as your "wobble area.")
3. Put smooth, consistent pressure on the trigger and let the shot go off when it wants to. IOW, don't jerk the trigger as your sights get close to the center of the target.
4. Learn to memorize where the sights were on target when the rifle fired. This will teach you to "call your shot." That way you will know for certain when you fired a bad shot. Then when you fire a bad shot, forgive yourself and go right back to the previous techniques.
5. Keep aiming long enough so the bullet has time to go through the target, after the shot is fired. This ensures you have good follow through.
For some reason, the "lights finally went on" for me on this during the NRA course mentioned above.
Using these techniques, I went from low Expert to Medium to High Expert with a pistol and from medium to High Expert with the Rifle. Matter of fact the next time I shot the Rifle for re-qualification, I was the 8th Marine in history to tie the All Time Range Record of 249 out of 250 at Quantico back in the mid 1980's. BTW, that record is still current as of a few months ago.
OH, I taught this to my young Marine Armorers when I got it cleared for them to qualify with the Pistol. NONE of them had ever fired for qualification with a pistol, though my NCO's had familiarization fired a few times. Every last one of them at least qualified Marksman and half of them shot Expert. The Range Coaches were stunned, as that was far better than normal and especially since my Marines were doing it for their first time.
Gus