Stay safe
Staying safe is important.
Natural hazards
Weather
Make sure to bring enough water when going into a desert.
War zones
Better just avoid them. If you insist... well...
Criminality
Robberies
In countries and cities that are known for robberies it can be a good idea to use a separate wallet. Another option is to keep a stash of something between 20 and 50 USD at hand to quickly "buy" your way out.