These are the four rules of gun safety. I keep these rules printing on my wall where I store my firearms not because I forget them but to remind me the importance of gun safety.
1. Treat all guns as if they are loaded.
2. Point the gun in a safe direction.
3. Keep your finger off the trigger.
4. Know your target and what's behind it.
Also,
5. Know how to operate your gun (safety features, field strip)
6. Store you guns properly, locked and unloaded.