Verified clear, at home, in a garage or out of public view. Use your vehicle as the obstacle. Fifteen reps of moving from the driver's door to the engine end of the car and getting low behind the front wheel. The engine and the wheels are what stop things. The doors and the glass do not.
Twenty rounds at 10 yards from a barricade if your range has one, two per exposure, working low. Otherwise shoot from kneeling.
You know this from training. The part to rehearse is getting there quickly in winter gear.
In a parking lot, the car is the cover you actually have. Know which parts of it count.
A rifle rested over a hood shoots lower than you expect because the sights sit above the bore. Keep the muzzle clear of the hood.
AUX (when ready): move to the front wheel and make two hits from kneeling in under six seconds.
Know which parts of a car will stop a bullet and which will not.
Get behind the engine. Then decide what to do next.
Look at where the other cars are. They are cover and they are also places to hide.
Put the engine between the problem and your family.
The engine and the wheels count and the doors do not. That is the whole rule.
Layer: work from the other end of the vehicle.
Dry-fire: no ammunition in the room. Verify the firearm is clear — twice. Use a safe backstop. When you finish, say it out loud: “Dry fire is over.”
Non-negotiable. Every drill, every rep, every time. This applies to live fire and dry fire.