Eye dominance is a critical component. If you don't understand what eye is dominant you are not going to reliably hit your targets.
Hold your hands out in front of you, palms open with your thumb/forefinger at 90 degrees (shaped like an "L").
#### your hands in 45 degrees and bring your hands closer together until the "y" of your thumbs forms and open triangle of light about 2" across.
With arms still extended, look through the hole in your hands at a fixed point about 15 feet in front of you (light-switch, wall plug, something similar sized to those).
Looking with both eyes open, close your right eye. Does what you are looking at dissapear? If so, you are right eye dominant.
If it stays in your field of vision when you close the right eye, you are left-eye dominant.
Once you know this, you will know which eye to use when you line up your sights.
For example, if you are right handed and left-eye dominant (cross dominance) then you know you need to turn your head to the right and hold the gun further left in order to clearly line up the sights and target and keep both eyes open.
the critical thing is keeping both eyes open.
If you can't do that, then you need to close your dominant eye in order to get a proper sight window.
for example, I am right hand/left eye. I can not shoot a rifle lefty, so I must use my right eye and close my left to keep it from taking over the sight picture.
With a bow, because you MUST line up the string with your dominant eye, I had to learn how to shoot left handed in order to attain a proper sight alignment.
It all depends on you, how ambidextrous you are, and if you are trying to align a proper sight picture or not.
Regardless, if you do it properly, and practice till you are comfortable, I guarantee you will improve if you apply it properly.