http://blog.beretta.com/Shooting-Tips-Accuracy

http://www.jprifles.com/bulletin/propost_october_2015_01_01.html

One Eye Or Two? This articles Say...TWO! However, we need some time and practice to switch our brain from one eye to two eyes shooting. Regular dry-fire practice is the fastest method to learn shooting by two eyes. But read this article to avoid handgun damage:

http://blog.cheaperthandirt.com/dry-fire-practice-is-it-safe-for-your-firing-pin/

P.S. If you have a hummer fired handgun, I would additionally recommend putting a piece of the pencil eraser between a hummer and striker. Periodically changing the eraser, we can exclude the possible strike deformation during very extensive dry-fire practice and decrease the sound of the hummer, which may irritate our relatives.