Step 1, be prepared!: Now don't jump out of your seat and run to the ammo store, at the moment there are no inclinations of a nuclear threat. But in the near future there may be. But when the next big war starts, stock up on non-perishable food items and ammunition.

Step 2, get out of there!: There should be emergency broadcasts on the tv, radio and computer telling you if a country has launched nuclear weapons. If you live in a big town/city grab a few belongings and get out of there! (Or if there is a nuclear bunker in your city go there.) The first nuclear targets are probably going to be New York city and Washington DC. So if WWIII starts you better go live with your grandmother somewhere. If you live in a small town than lock your doors and hunker down. (Do not go to any stores, there will be looters there and most of the food will have already been stolen, so stay indoors.)

Step 3-A, all goes well: There is a possibilty that the government will still be intact. Just wait in your home and if the power's still on turn on your tv. Government aid may arrive soon and the apocalypse will have been adverted.

Step 3-B, all goes wrong: But more likely than not, the apocalypse will happen and modern society will crumble. Board up your windows and try to scavenge some food, there is a possibility that your town will form a colony and govern itself but there is also a possibilty that everyone either left your town or died.

Step 4, survival: If your town has formed a government your best bet is to stay there, but if not, pack up your belongings and head south. It is warm there so you don't have to worry about heat. The best modes of transport are trucks, SUVs and motorcycles. Try to find some ciggarettes and alchohol, these will be very valuable and (if you find someone willing) can be traded for weapons. You should try hunting wild animals or killing stray livestock for food. And stay away from major cities, these contain radiation which can kill you.