It's a HEAD GAME, not a GUN GAME

There were never truer words than those of the "creed". For those of you familiar with the phrasing, I left out the last line for the simple reason we are here to learn to DEFEND ourselves and our loved ones. The basic principle is that there are components of muscle memory that must be built to allow for accurate and efficient (smooth, not fast) shooting of a firearm, but the most important, most impactful, most pervasive is the mind/concentration/focus.
Every component of the 8 fundamentals requires a level of attention to pull them together and keep them consistent. If you lose focus for even a split hair of time, your aim will be off, your grouping will enlarge. Do not analyze each shot, finish the series, each bullet is a new trial.
Stance
Grip
Draw/presentation
Breath control
Sight alignment and picture
Trigger control
Follow through
Recovery
Dry fire is the key to cementing in these muscle memories and keeping focus on the mechanics and not the impact, sound, sight, adrenaline. Making sure you have cleared all ammunition from the firearm and the room, that you are using a dummy cartridge if you have a rimfire firearm and never practicing in a way that puts your muzzle in line with something you are not willing to destroy, practice constantly.
Stance should be stable with shoulder-width apart feet, weight forward slightly and knees loose but sturdy. Like you are ready to move in any direction at a moment's notice. If you can be pushed off balance your stance isn’t right.
Grip is two-handed with the webbing of firing hand to the top of the backstrap. Trigger finger along the frame and remaining fingers loosely curled below the trigger guard. The support hand is then tilted down to cover the remaining exposed grip wrapping all four fingers over firing hand below the trigger guard. If done right the middle knuckle of your support hand's first finger should be resting on the lower edge of the trigger guard. From here you want to use that support hand to create a clamp on the pistol grip. Pushing into the support hand and pulling back against the firing hand. This allows the trigger finger to remain independent in its movement from your grip and gives good solid control front to back and side to side of the firearm. You should not GRAB your firearm, but have it clamped between your hands- this allows your trigger finger to remain loose and reduces excess tension that can cause muscle fatigue and increased tremors/shaking.
Draw and presentation. This is key to have comfort with and consistency if you are carrying defensively. Always maintain your holster and carry location in a similar place. It becomes muscle memory to draw from that location and saves crucial time when you do not need to be focused on, "now where did I put my weapon?" when those microseconds could be the difference between defense of your life and being too late. Practicing to smoothly and safely draw your weapon to target without having to look for it allows you to keep your focus and attention on the threat. Practice with concealment and how to clear that from your way, be it a jacket front, shirt hem or other obstacle to how you carry.
Breathing is essential to life in so many ways. It brings clarity to your mind, energy to your cells, releases tension that can build distraction and focuses intent. If you aren't breathing, your trembling, your vision goes dim, your ears fade out, your heart races and so many other physical effects. There is a natural point of pause in breathing. Just after you exhale, while circulation of gases exchanged in the respiration of your lungs settles out and you prepare to inhale again. This moment of stillness is the time to act, the momentary platform of stable transition most likely to allow your aim to remain steady. Practicing using this moment will help in marksmanship but will go out the window in a real-world fight.
Sights, aiming and sight picture are usually the first thing people think of when talking about mastering their target and hitting accurately, hopefully by this far into the article here you have discovered this is only one part of the process. There are several ways to describe aiming in your sights from marksmanship dominant eye only to defensive accuracy to instinctive aim. All have their place and uses, but with all things you need to start with the basics and work up to the point of being able to point and shoot and hit every time.
The front sight is the key- where it is on the target is where your bullet is. If it is leveled above the rear sights your bullet will be high, if it is off toward one or the other rear sights and not equidistant, so will your bullet. If you can accurately see the lines on the target, the wrinkles on the perpetrators forehead or the dents in the steel plate, you are not focused on that crucial front sight and your aim will suffer. We ask all new shooters to focus on your dominant eye and close your weaker eye to help improve your concentration on that front bit of metal on the barrel. Much like blinders on a racehorse keep it from reacting to the competition, grandstands and flags waving. Not only do you sometimes get double vision focusing so closely on the front sight if both eyes are open, but you are tempted to focus beyond that ridge to the target it is superimposed on. Once you can accurately hit consistently with that frame of reference, then you can consider trying both eyes open and working to aim where you look. Now this doesn't indicate you have graduated from dominant eye work- it is always good to rehash the basics and reaffirm you are on top of things, but once the mechanics are ingrained it will become second nature to aim where you look.
Defensively, never close one eye, we want the best hit on center mass, not a small grouping on a distant ring, so make sure you are alert and responsive and use both eyeballs and all your brains in a defensive fight.
Control of your aim through a slow smooth trigger is the most efficient way to maintain your accuracy, even when you start adding speed. You are never telling a gun to fire with your trigger finger, you simply ask it to fire and keep adding pressure until it responds. When you try to force it to go off "now", you risk jerking your finger, your hand, your weapon and pulling your sights and aim enough off target to reduce your accuracy appreciably. The best way to practice starting out is to distract yourself from that desire to get results- count as you squeeze back on the trigger, repeat a mantra of slow, slow, slow or front sight, front sight, front sight. Let your firearm surprise you, that reduces your need to force the response and twitch or move. The tortoise and the hare analogy are accurate in many things. Slow steady pressure on the trigger will get you a more accurate shot everytime. Have you ever watched a long distance rifleman slap down his firearm and start squeezing off rounds? No. They set themselves up, check for windage, elevation, etc and then once ready, breathing in and out, they settle in and very slowly squeeze until the shot is fired, release and reset to another round. Keep that in mind, a handgun operates no differently, but is much less steadily supported in your two hands than on a benchrest or sandbag.
Just like any other sport you have to follow through to maintain the accuracy of your ball, bullet, etc. Have you ever seen a hook shot in basketball make the basket when the player stops their arm as soon as the ball leaves contact with their hand? Ever seen a baseball go out into the field when the swing stops at the "whack"? Or a bowling ball actually travel ANYWHERE if you just drop it from your hand? No. The act of stopping at that point requires your momentum to decelerate and changes the arc of the forces you are applying to the ball, bullet, object you are propelling. But, if you follow through the full swing, full motion the forces will continue that path. In martial arts, if you were to try and break the board by striking the board and not striking THROUGH the board, your hand is going to be hurting and the board won't budge. Because you impercepitbly slow your motion to "stop" at the board, but if you aim for the air beyond, you are at the height of your force as you strike and pass through the board. In shooting, follow through is bringing your recoil back to target, back to that perfect sweet spot of accurate aiming. Ready to followup on the next shot. Practice shooting in pairs. Do not fire one off, drop the gun and look for where you hit. You will pull your aim off each time. Return and fire off a second shot, then regain that aim. Then you can look at your results.
Recovery. I like to think of this as that time after the follow through. Where you are on target and breathing again. Taking a moment to settle into yourself before judging your results.
But, when you are not on the range and in a safe environment, recovery is a whole different thing. In defensive shooting, the recovery time is when you want to implement and practice after-action sequences. Just because you have stopped the attacker in front of you, doesn't mean that there is not another possible situation around you. Do not lose yourself in the tunnel vision of your opponent and the shooting. Keep your firearm at a low ready and look around. Is the attacker still in the fight and trying to rally? Are their other attackers at your periphery? Is there a cover or concealed area of safety you can get to? If the fight is truly over, this is the time to call for help, apply first aid where needed and secure your firearm and that of your attacker where they cannot be used against you until that help arrives. Do not tamper with any evidence, but make sure you are safe.
Hopefully this rundown of basics and the concentration and mechanics in each has highlighted to you the importance of using your eyes and brain to fire consistently and accurately. And has encouraged you to practice the finer points of marksmanship, no matter your discipline, area of sport or desire for defensive practicality.