The most stable body positions for firing are: standing, kneeling, sitting, and prone.
To "zero" your weapon, you must have a proper sight picture.
Sight corrections are made after three rounds have been fired.
In adjusting your weapon sights, you must keep in mind the following rule: if the setting is for front sight, it must be moved forward toward the shot group; if the setting is for rear sight, move it away from the shot group.
If you don't memorize your zero setting, you'll have to zero your weapon after each cleaning.