Welcome to ETS!
My preparations are aimed at short-term (less than three days), and medium-term (three weeks or less) emergencies. A complete break down of society over a long term is not something I'm planning for.
In my neighborhood, we've banded together and helped each other out during several weather emergencies and power outages. I fully expect for our little corner of society to continue operating in future short- and medium-term emergencies.
If I were you and planning for a complete breakdown of society, I'd be moving out of the suburbs into a rural area with water and the ability to grow your own food. I'd be investing in tools, stored food, medicine and survival skills. Keep in mind, though, that it's very hard to provide for your security when you don't have good neighbors.