If you decide not to shoot, remove your finger from the trigger, before anything else. Then lower your gun and holster it. Never keep your finger on the trigger when handling your gun. Inserting your finger in the trigger guard and resting it on the trigger should be your last move, before you shoot your target, your gun must be pointing to the target before you put your finger on the trigger. Never holster your gun, with your finger on the trigger.
Every gun is different than the others.
Some are revolvers others are pistols, some are single action, some are double action devices. Learn how to use your guns. Learn how to load it and unload it, how to strip it, how to put it back together. Learn the way it works. Familiarize yourself with the gun, even to the point that you know it blindfolded.