Jeff Cooper, father of the Modern Technique, formulated the following four safety rules. They have been tested and tried and have proven to be the gold standard for firearm safety. There are only four of them. Commit them to memory and more importantly: IMPLEMENT them.
Every accident that I have witnessed has been a direct result of ignoring one or more of these safety rules.
Robbie Barrkman
1. All guns are always loaded. Even if they are not, treat them as if they are.
2. Never let the muzzle cover anything you are not willing to destroy. (For those who insist that this particular gun is unloaded, see Rule 1.)
3. Keep your finger off the trigger till your sights are on the target. This is the Golden Rule. Its violation is directly responsible for about 60 percent of inadvertent discharges.
4. Identify your target, and what is behind it. Never shoot at anything that you have not positively identified.
Jeff Cooper's Commentaries, Vol. 11, No. 4, April 2003