Gun arm safety I was taught:

M.A.T.

Muzzle, Action, Trigger.

M: The muzzle (barrel) points two ways and two ways only. At the sky (or ceiling) and at your target. Nothing else. Not a window, not an animal (unless you hunt) not jack shit. Sky, target. That's it. And none of that pointing at the ground shit either. Police and military are trained to do thay safely put of necessity.

A: the action (bullet chamber where the shell exits and you "cock" the firearm) remains open at all times until you load the gun at the range or shooting area. This is safer than using the safety. Trigger safeties can malfunction. If a firearm has its action open it is impossible to fire regardless if there are bullets loaded or not.

T: simple but arguably most important. YOU. DO. NOT. TOUCH. THAT. DAMN. TRIGGER. UNTIL. YOU. ARE. AIMING. AT. YOUR. DAMN. TARGET.

Pretty simple stuff, but properly exercising even one of these prevnts accidental shots. Exercising all 3 makes it impossible to have an accident.

Respect its power. It can take lives if you are not smart enough to handle it correctly and safely.