Col. Jeff Cooper distilled gun safety down to four simple rules.
1. All guns are always loaded.
2. Never let the muzzle cover anything you are not willing to destroy.
3. Keep your finger off the trigger till your sights are on the target.
4. Identify your target, and what is behind it.
Chance Ballew adds one more to that list: Do not try to catch a dropped gun.
I think Col. Cooper would have approved the addition of Rule 5 if he were still with us.