Preparing for the worst means a lot of different things to a lot of people. I submit that the first thing you have to acquire is a new mindset. The mindset I refer to is, "How are we going to make this work?" Whatever "this" is. Think of what you NEED most in life and start there. You NEED air, water, food, clothing and shelter (in that order). It seems kind of silly to list "air" but don't leave any consideration out in your planning. You may want to pack gas masks or oxygen tanks. It just depends. Having said that, how do you supply those needs. I plan to address those kinds of things in this blog over a period of time. There is a lot to it. I would like to mention that my own mindset changed when I started learning how to get along in the woods with just my knife, so that colors my ideas. In fact, I suggest you start learning just that. We have to start somewhere and that is a real fine place to start. Scenario: You are lost in the woods. You only have what you are wearing and a knife. What do you do? This is the beginning of planning for all sorts of problem situations. I recommend a book that will help a lot: Wildwood Wisdom by Ellsworth Jaeger
This is a great starting point to using materials at hand to take care of yourself.