Okay, here's a thought, about a process I went through.
You know how everyone says it's important to have a "disaster plan"? Of course it is. You put together a "go bag", for example.
Start with the scenario: you have to leave your house 60 seconds from RIGHT NOW, and anything left behind may well be completely destroyed. What do you grab? Obviously this is very minimal and requires pre-planning.
But then, expand it to: a category 5 hurricane is bearing down on your city, which may now become the next New Orleans. It's time to go, but you have the rest of today to pack the car. Make your list. Remember that all of it, including people, has to fit in the car.
Now, aside from being prepared for the worst, you have a nice list of the things that are REALLY important, and there's your starting point.