Don't accept objects from strangers, like flowers, to avoid tourist scams in major cities like Rome and Paris.
Use public transport or Uber instead of renting a car in major capitals.
Be respectful at Holocaust memorials and museums and avoid taking photos or videos.
Store your wallet in your front pocket to avoid pickpocketing.
Don't expect stores and restaurants to be open all the time like in the US.
Be mindful of cultural norms and avoid being loud or rude, be polite but direct about what you want
Avoid falling in canals and blocking bike paths in the Netherlands.
Don't eat at restaurants in touristy areas with photos and prices featured on the window.
Avoid buying an overpriced international phone plan and purchase a cheap sim card at the airport.
Don't split airport cabs with random people to stay safe.