1. Unfamiliar foreign currency stresses people out.
  2. Selfie sticks are an abomination. Use your arms.
  3. After a long day of walking people just want to stare at the wall and eat a crêpe in peace. And that's okay.
  4. My younger brother has a nearly perfect Bob Dylan impression.
  5. Two photographer parents in an historic famed city are like toddlers: behind you one minute, gone the next.
  6. Never try to run onto the tube as the doors are about to close. Not everyone in your party will make it on. See above.
  7. Paris is as beautiful as it is smelly.
  8. Always leave for the airport 20 minutes before you think you have to.
  9. Try to go as long as possible without using the Internet. You may get lost but it will force you to talk to people.
  10. Never underestimate the restorative powers of a hot bath.
  11. If you aren't French, your French accent is terrible even when it's perfect.
  12. Never pee without paying.
  13. Don't tip in England. Do tip a cabbie when they get you where you need to be without excessive detours. This is a rare occurrence. You have encountered a wizard.
  14. Drink water. Ask for more water. Repeat. You don't realize how ubiquitous water is in America.
  15. Oh, you want ice in your water? That's adorable.
  16. Lastly, always get a cup of coffee if it is offered in Ireland, because while it may not be as good as the coffee in France, it will come with the crumbly ginger-snappy joy that is the Belgian Biscrip Cookie. You will love this cookie and want to have its children.