1. Assess your supplies.
2. Make sure you have foods that are well preserved and can last you for an extended period of time.
3. Make sure you have lots of clean drinking water.
4. Once your supplies are secure, safely investigate your surroundings.
5. If you see anyone else who can be aided without harming yourself, do what you can to help.
6. It is very important that you ration out your supplies to last until you can acquire more, or the risk of danger is eradicated.
7. BUT, if it's really, really the end of the world, fuck it.