Check your passport expiration; you may be denied entry into certain countries if your passport is due to expire within three months of your ticketed date of return. Get it renewed if you’ll be cutting it close.
Make reservations well in advance, especially during peak season, for accommodations, popular restaurants, major sights, and local guides.
Call your debit- and credit-card companies to let them know the countries you’ll be visiting, to ask about fees, and more. If you don’t know your credit card’s PIN code, ask your bank to mail it to you.
Do your homework if you want to buy travel insurance. Check whether your existing insurance (health, homeowner’s, or renter’s) covers you and your possessions overseas.
If you’re bringing the kids, make sure you have the right paperwork, including a passport for each, a letter of consent if only one parent is traveling, and documentation for adopted children.
Make copies of important travel documents as a backup in case you lose the originals.
Students should get an International Student Identity Card for discounts.
If you’re planning to buy a rail pass, you’ll need to get it before you leave. Rail pass or no, it can also be smart to reserve seats on certain trains before you leave.
If you need to bridge several long-distance destinations on your trip, look into cheap flights. For the best fares, book these as far in advance as possible.
If you’ll be renting a car, you’ll need a valid driver’s license.
If you plan to use your mobile phone or smartphone, contact your provider to enable international calling or to “unlock” your phone. Consider signing up for an international calling, text, and/or data plan, and be sure to confirm voice- and data-roaming fees.
Get a proper guidebook.
Download any apps you might want to use on the road, such as translators, maps, and transit schedules.
Take care of any medical needs. Visit your doctor to get a checkup, and see your dentist if you have any work that needs to be done. If you use prescription drugs, stock up before your trip. Pack along the prescription, plus one for contact lens or glasses if you wear them.
Attend to your household needs. Cancel your newspapers, hold your mail delivery, and prepay your bills.
Give a copy of your itinerary to family or friends.
Make a list of valuables that you’re bringing (such as electronics). Include serial numbers, makes, and models, and take photos of your items to serve as a record for the police and your insurance company should anything be stolen.