While not all restaurants fall under suspicion, be wary of eating at 'roadside stands' or snack bars. If the food establishment is holding or serving foods at midrange temperatures, walk away. If this happens while en-route, you will be thankful you packed that snack. Be aware, each country has slightly different guidelines on health and sanitation of food, water, and beverages. It is hard for almost everyone to adapt to new 'food bugs' in their system but, for those with preexisting illness, the consequences of unfamiliar germs can be much more than simply 'unpleasant'.
Food borne illness or water contamination can be life threatening.
Be especially wary of local water, ice cubes, fresh fruit without a heavy skin that can be peeled, and raw vegetables. Also, bring an electrical outlet adaptor to ensure the devise will work using any electrical outlet since currents or voltage can vary. When inserted into a mug or heat-resistant container with cold water, the heating devise should be able to heat water to a boil. Ice should be made only from boiled water. Fresh fruits and vegetables may need to be avoided.