Have a plan.
Lots of people fail to do what is needed in unusual, potentially fatal situations, because they just didn't have a plan of action ready. Many times, given a cool head and a minute, they could have devised a workable plan in less time than it takes to consume a cup of coffee or a cigarette. But in the heat of the moment, none of us thinks our best (no, not even YOU, Mr. Armchair Warrior), and that's not a good time to think. It's the time to act on what you have already thought out.
Would it be better to perform a preventive drill before? Sure. But when you get right down to it, there's just too many "what if's" to be able to drill for them all. What if your neighbor goes nuts and drives his pickup into your family-mobile while you're en route for ice cream? Are you going to practice rolling out of your car and shooting over your hood while your family egresses from the off-side of the threat? Are you going to practice this in your neighborhood street? What if the threat is your neighborhood Cujo, attacking your neighbor? What if the threat involves... uh... lava? Yeah, molten lava?
Okay, that brings up another point-- there's a point where we have to just stop. We can't live in constant concern of the world and how to deal with it. There are things you're just not likely to need to deal with. In N. Texas, lava isn't a real concern. In Hawaii, I'd give it a thought.
Think about how you'll deal with a given situation. If nothing else, it makes your day more interesting. And believe it or not, if you win [?] the lottery and the unlikely occurs, you'll have what amounts to some experience in the situation. Because, in a way, a part of you has seen it before, and you know how to deal with it.*
My dad and his bride noticed a spike in reports of a new method of home invasions in his area. They discussed it, and have a plan formulated. Is it the BEST plan? Oh, I can think of some ways to improve it. But because they have a plan at all, I'll bet on them, if the balloon goes up.
*Yes, I know that I've harped on this before. But advising people to "have a plan" is worth repeating, don'tcha think?