Find resources where others don't look.

Surviving a disaster is all about being smarter than the next guy. This means exploiting resources that others will overlook.

Lets say its a disease, a global pandemic.  The first thing that will happen is everyone flees the city looking for somewhere safe. Anyone who's seen a zombie flick can get an idea of what the highways would look like. Thousands of abandoned cars packed together, never to move again without the gas they need to run. Cars can be a huge resource reserve, even a nearly dead battery can be used to get a fire going. But what I'm thinking about is years after. Well past the point that you could use the small amount of fuel in the tank or the electrical system.

If you look at newer model cars, many are equipped with projector headlights. They use a parabolic lens to focus light instead of a large reflective housing. They're very easy to spot, it looks like a glass orb behind the lens. These make a great magnifying glass, and we all know you can make fire with a magnifying glass.

So find a suitable lens, grab a rock, and at midday you can make fire. I used the lens pictured to light a cigarette in about 20 seconds.