There are a fw tings to remember. Always.
Treat the firearm as if its always loaded
Never point the firearm at anything you don't intend to destroy
Always point downrange
The safety stays on until you're ready to fire, finger off the trigger
Clear every firearm everytime when handling or handing to someone else, never take someones word for it and check for your self
I'm sure you can clome up with more stuff, but these few things will help and are good to keep in mind. Ill also add, if the firearm jams, won't cycle a shell out of the chamber, or goes "click" on a shell but not "boom", never put your face infront of the muzzle, nor should you ever turn around where the gun may point at someone else. Defer to the rule about always pointing down range.
There are some finer points of stance that will greatly improve your ability to handle the firearm. For example, maintain 4 points of contact, which I'll explain.
1. Trigger hand on the grip, pulling the gun into;
2. the pocket formed between your chest and sholulder
3. Support hand on the forend pushing forward on the gun
4. Your cheek solidly on the stock
Your stance is also important. Wing and sport shooting, the traditional stance is to stand "bladed" with the gun sorta goin across your body. But when shootin and practicing for HD, stand with your body and shoulders sqaure to your target. Bend your knees slightly, your dominant foot slightly behind the other, and lean into the gun. This will effectively help to reduce felt recoil by transfering the energy through your body.