If you’ve figured out a way to travel abroad without the use of money, please let me in on your secret. Otherwise, you’ll need to have a plan to pay for things. Unlike in the US, credit is not always the default method of payment in all shops, restaurants or vendors abroad. It’s generally a good idea to ask, prior to a transaction or at the beginning of the meal, if credit is accepted, if that’s how you’re planning to pay. It’s probably best to keep a bit of cash on hand while you’re out and about (although, be safe and wise about it) because that’ll be accepted everywhere. Many ATMs will accept US debit or credit cards (but watch out for large “cash advance” fees if using the latter) but it’s best to investigate how best to access your cash before you depart.
For example, we were shocked to find out that the grocery store, convenience stores and many restaurants did not accept our American credit cards. Also note — it’s likely, and perfectly normal, for any health services (like a doctor or hospital) to expect you to pay the bill in cash at the end of the service — it’ll be up to you to work things out with your health insurance when you get home (so make sure you get a receipt). It will also probably cost you much less than you expect it to, so don’t worry too much about it.
(And, after almost 2 years here, this still occasionally comes back to bite us . . . )