Marksmanship principles are the basic ideas behind being a proficient shooter. Here, I shall list them and then elaborate on how they apply to rifle shooting.
1. The position and hold must be firm enough to support the weapon.
Naturally, the firmer a shooters position is, the more successful their shooting will be, as the rifle will move around less of its own accord and will instead stay still. In target shooting, the position can be supported by a sling running from the shooters bicep to the rifle preventing their left arm from moving forward and taking some of the strain and weight of the weapon.
2. The weapon must be pointed naturally at the target without undue physical effort.
No physical exertion must be required to make the weapon point in the direction of the target, as it will result in the rifle moving around unsteadily. Instead of forcing the rifle left or right to point in the right direction, moving the hips or the legs will move the position so the rifle is naturally aligned. To ensure the rifle is aligned naturally with the target, a shooter can close their eyes, breathe in, relax, and fully ex-hail before opening their eyes. If the rifle is still pointed at the target, it is naturally aligned.
3. Sight alignment must be correct.
Contrary to popular belief, sight alignment is NOT the same as aim. Sight alignment is the relationship between the eye, the rear-sight and the foresight. The foresight must be in the middle of the rear-sight. Altering the distance of the rear-sights from the eye, or the rear-sight aperture can give a clearer sight picture to make this easier.
4. The shot must be released and followed through without disturbing the position.
Triggers should not be pulled. They should be squeezed. Even if a shot was perfectly aligned to hit dead center of the target, yanking the trigger back roughly will move the rifle away from the target as the shot is fired. Depending on the weight of the trigger, pressure may also need to be applied by the thumb onto the stock as well as onto the trigger in a squeezing motion.
Now onto follow through. Having pulled the trigger, a few moments should be spent allowing the rifle to recoil and settle back into position before the shooter moves, as to not disturb the fall of shot.