The four basic rules of gun safety. There are many more specific issues related to gun safety; however, these four, mostly borrowed from Jeff Cooper, distill it down to the essentials.
1. All Guns are always loaded. [Treat them that way]
2. Never let the muzzle cover [sweep] anything you are not willing to destroy.
3. Keep your finger off the trigger until your sights are on the target.
4. Be sure of your target. [And what’s behind it]