Before you leave, take some time to question yourself. In-depth preparation will help you avoid some nasty surprises .
Better to fill a few papers than to have some worries
See with the embassies the conditions of entry into the country. In Russia, for example, you have to pay, have a job and a passport with a validity of more than 5 months. Same thing for some US states where you need a passport with a validity date of more than three months to return. For Japan , like other countries, a simple passport and especially an exit date will be awarded (3 months maximum).
Ask your bank, depending on your type of card, you may not be able to use it abroad. On the other hand, banks have effective repatriation services, ask if you benefit.
Contact the CPAM. There is a universal coverage system across Europe for your health costs to be covered. You will need to fill out a form in advance.
From a material point of view
Buy a charger adapter for your phones , just in England you will need one.
Take cash on you: Italy for example works a lot with, including station automat. Other economically undeveloped countries may not have many cash machines available. Do not put all your money in one place, no one is safe from theft.
And finally, for those who will leave by car, think to do your technical control! You will be able to be serene and safe. Depending on the routes you take, your car could be put to the test!
Here you are, ready for your trip, enjoy your stay.