Be mindful of pickpockets especially in Paris!
When you travel through France by train, you often have to get off at one train station in Paris, and take the Metro to another train station to continue.
This funnels a constant fresh supply of disoriented tourists onto specific Metro routes.
When you’re in one of those Metros, there will be groups of professional pickpockets on board.
And if they can’t pickpocket you, they aren’t above shoving, crowding and yelling at you to take your focus off your wallet.