IMHO the first lesson is that strong building codes written with a critical eye toward the hazards of an area and firmly enforced saves lives. Immediately after a disaster undamaged buildings that can be trusted are extremely valuable resources. The difference between 10% and 90% of buildings down is tremendous.

Second, weather makes a difference. One saving grace of the Haitian location is that it is not freezing cold or burning hot. Imagine how much worse it would be if it was below freezing at night. Fortunately, so far, storms are not an issue. Imagine if a hurricane came through 24 hours after the earthquake.

Third, sturdy, well built infrastructure like water, sewers, roads, airports make a difference. Haiti doesn't have any of these and is suffering more because of it.

Fourth, extreme poverty makes everything worse. People who are living close to the edge have a short way to fall before they fall off and perish.

Individuals, other than generally lobbying for strong building codes, infrastructure and actions that help take the rough edges off poverty, cannot do much to change any of the above. But one might imagine what this disaster might have looked like if even a third of the people had even a minimal three-day kit with a couple of cans of beans for food, a few liters of water to drink, and a couple of bandannas that might be pressed into service as bandages. They would not be a total solution but they might have served to take the ragged edge off the suffering as more definitive relief was organized. A little available now can mean a lot to those who have nothing.

So take heart and prepare as best you can when and where you can. If all you can manage is a bottle of water and a can of beans then do that. If you can manage more so much the better. Just because you can't afford to spend thousands of dollars laying in huge amounts of equipment and supplies doesn't mean you can't make a real difference if and when disaster visits.