Keep in touch with your friends and family and share your itinerary with them, especially if you are traveling alone.
Never keep all your money in one place. Instead, spread out your money and cards in different places so that if you lose a bag or your wallet, you're not stranded.
Keep extra copies of important documents and store them in the cloud in case you lose your phone or laptop.
You should always carry a first aid kit with you while traveling. Keep general medications for fever, headaches, nausea, etc. and items for wounds such as crepe bandages, gauze, etc.
You should remember your emergency contact numbers and some local numbers in case of an emergency.