This one, like water, seems obvious. I prefer to think of it as fundamental, in the same way that before they jump out of planes in the middle of the night, special forces operators learn how to run well. A lot. Getting the basics right will help you survive.

For food, I recommend something portable and sealable that lasts a long time. For example, since I live many stories above ground level, every once of unnecessary packaging is another ounce pounding on my knees if I need to bring it up or down when the power is out.