Notify Beforehand: Although not always necessary, it’s best to call your bank and credit card company before traveling to let them know when you’ll be out of the U.S. and in what countries you’ll be traveling. This will prevent possible rejection of transactions related to their fraud prevention systems.
Make Copies: You should make copies of your credit cards, ATM cards, identification and medical cards, etc. for each person and, I suggest, leave a copy with a friend or loved one back home. You should also enter the phone numbers on the back in your contacts folder. It’s a lot easier to report/replace lost or stolen items when you have of all information at your fingertips.
Credit Card Fraud: You should check with your credit card company about how they might contact you if they block a transaction they suspect may be fraudulent. This happened to my wife in Mexico once… she got a text from our card company asking her to confirm if it was a legitimate transaction. Because we had our regular cell phones/numbers with us, she was able to verify and complete her transaction.
Credit Cards with Chips: Just as in the U.S., using credit cards with embedded chips is a little different from the “old-fashion” swiping approach. Most points of sale in Europe support the chip technology, but be aware that some kiosks, require you to enter a PIN. So make sure to contact your credit card company to set up a PIN before you go.
Getting Local Currency: ATMs are prevalent throughout all of Europe, and many major U.S. banks have “affiliate” relationships with banks in other countries. For example, Bank of America and Deutsche Bank have such an affiliate relationship. When such a relationship exists, you can often use the affiliated bank’s ATMs and not pay any transaction fees. You’ll typically also get the best exchange rate when using ATMs regardless of any affiliation.
Bank ATMs: Always try to use ATMs associated with a bank (affiliated or not) as they charge the lowest fees and provide the best available exchange rate.
Daily Withdrawal Limits: Be aware of your daily withdrawal limit (e.g., $300/day) and do some rough math to know how much you can pull out per day in Europe. For example, if it's a $300/day limit, then you can pull out a maximum of about €260 per day (at late 2018 exchange rates). Also plan on being able to withdraw money only from your checking account so transfer what you think you need before you leave.
ATM PINs: European keypads have only numbers, so you’ll need to know your personal identification number (PIN) by number rather than by letter.
Exchange After You Land: No need to exchange any currency before your trip as all airports have currency exchange services (not the cheapest way to get local currency) and typically several ATMs (definitely the cheapest way to get local currency). That said, it’s always best to use ATMs associated with a bank as they charge the lowest fees and provide the best available exchange rate.