I do something similar, including keeping enough local cash to survive for a day or so if the banking network goes down. (This has happened to me, for example in Mexico City and Norway.) I always have a charge card or credit card with me on which I can buy a full fare ticket home if really needed. To me, it's reassuring to know that my cards come with some emergency services. Basically, I want to be able to evacuate myself if necessary.

IMO, perhaps the most important thing is to be aware of the risks for your itinerary. Pay attention to any expected polical demonstrations/uprisings, anticipated big crowds or really bad traffic jams (don't unknowingly try to drive north on the autoroute to Paris on August 31st with only a quarter tank of gas), epidemics, weather hazards (when is tornado/hurricane season and how is information communicated?), food and water safety standards, crime levels, special local risks, etc. For example, I'm shocked when people go hiking away from home without any idea whether there are poisonous snakes in the area and how to recognize and avoid them. The same can be said for arriving without hotel reservations into a city that is obviously and predictably sold out.