Select the events to plan for. Organize the events according to which is most likely. This requires a few things from you, an open and honest mind; and research. What you think might be the most likely event, might actually be fairly rare. During this phase it is good to have a second person whose judgment you trust, to question the order of events to prepare for. By including another person the list will be more useful and more accurate.
The list events to prepare for will vary from region to region, but in theory you neighbor should have close to the same list that you do. While your neighbor might have a different equipment and supply list, he will most likely be preparing for the same disturbances that you will be preparing for.
You can then classify the events in the preparedness spectrum (Personal disturbance, Local disturbance, National disturbance, Regional (multi-national) disturbance, and Global disturbance.)
During this phase is when you will want to take into account disasters that can happen near your local area, but not to your local area. For example, the recent evacuation of New Orleans. There are places that are six hours away and those hotels are filled with people. Keep in mind that disasters like hurricanes affect everyone in the region, not just the area being hit. While you might be hours away from New Orleans, you still could be affected in several different ways. Everyday supplies could be hard to find and even the criminals have to leave town when there is a mandatory evacuation.
Without a priority list and action items your attempts to prepare could be haphazard, contain blind spots, or even dangerous to those you love.
NOTE: The reason I suggest utility as the guiding principle for choosing which events
to plan is because most people have limited time and resources to prepare. Of course,
if you are one of the select few that has very few limitations, then by all means
prepare for the worst possible case (i.e. Nuke strikes and total societal meltdown).
NOTE: I also had written this before I read this. Though they say very close to what
I said, but they left out the important prevention step.