I guess the firdt thing is that you can't count on the police when all hell breaks loose. They are not equipped for that and the national guard is needed.
After hurricane Andrew, there was quite a bit of looting going on. When it comes to looting grocery stores, it is almost understandable if you have to feed your family. You can say it was their responsibility to stock up, but what about those who could barely make enough to pay rent? Besides, power was out in some areas for over 3 months. The people that made me sick were those looting the non-essentials. It just became a free for all.
I guess one of the best things to do is form a neighborhood watch and barricade streets. It helps if you know you neighbors before hand and hopefully your neighbors are not thugs. I live in a gated community which only has 2 entrances. That makes it pretty easy to control. If the poop really hits the fan, then we could just post a few guys to control who comes in. For visitors, we could probably have them escorted to ensure they are going where they say they are going. Resources would probably have to be shared to prevent some from going without (getting desperate). I do live in a pretty good area and fortunately we are not that close to the bad areas.
For those not in gated communities, I would still block off both ends of the street and form a neighborhood watch.
The ATF should be a convenience store instead of a government agency!