18. Wear a watch
Phones are great, except when you’re traveling and they’re confused as to where you are, or which time zone, etc.
What’s better is to bring a watch that you can easily set for whatever the local time is, both while dealing with layovers on the way there and back as well as moving between countries. This also means you don’t have to deal with either bringing your phone everywhere or making sure it’s always fully charged.
So, just bring a watch.