2: Keep your finger off the trigger until you are ready to shoot.
With the very rare exception, guns don't just "go off." It's pretty basic, but there's a lot of people out there who still are very sloppy with their trigger fingers. If nothing else, just knowing that if that trigger gets pulled, the gun is going to fire makes me even more anal about keeping out of that trigger guard. Regardless of whether you use the "safety" or not, even if you have a round in the chamber, if the trigger isn't pulled, the gun won't fire. If you find yourself in a situation where there is a good chance the trigger might get pulled on accident (by brush or other impediments), then that gun should not have a round in the chamber.