Whenever you travel out of the country, you will be using a different currency. You'll need to change money once you get to your destination. The best way to change money is to find an ATM. After all, ATMs are nearly anywhere in the world today. Still, it is wise to check before you travel if you should take cash, an ATM card, credit cards, or traveler's checks to your destination.
Before you fly out of the country, it's a good idea to change a little money. You can change money at the airport, where there's usually a bank, money changer, and a few ATMs. Although traveler's checks aren't as widely used today as they were in the past, they are still a good thing to have just in case you encounter problems using ATMs or your credit cards.
ATMs in some countries won't accept foreign-issued ATM cards so it's a good idea research about this information before you leave. Check out government advisories online. Also, just because you can't get cash from an ATM, it doesn't mean your card is the problem. Remember, electronic transactions need to be sent and approved, and in less developed countries, it may that the cash machine you're using is having communications problems or it can't read you card. And maybe it's because the bank ATM ran out of money.
Driving to another country instead of flying? Find out where you can change money. Also try to find out if other currencies, like those of neighboring countries, are accepted in the country you are visiting.
Watch the exchange rate too. If it looks like it's going to dramatically change, you're likely to get a better deal if you change money ahead of time. And here's one more reason it's a good idea to change money before you leave: you can learn to become familiar with the new currency so you won't have to fumble around trying to figure out how much you're supposed to give as tip.
And if you end up changing money at your destination, don't try to do the familiarizing in public; wait until you get to your hotel room and you have privacy. Learn what the bills and coins are worth. And you become easy target for scam artists who will shortchange you literally because they know you're not familiar with their currency. There are also those who will take advantage of your ignorance of their currency and try to charge you too much for something.
When changing money in your destination, make sure you do so at official money changing locations. Don't try the black market money exchangers; you'll land yourself in big trouble that way. When you're at the money exchangers, take note of the exchange rates and how much they are charging for their commission.
One thing you should not do is exchange more foreign currency than what you need. If do, you'll lose money when you have to convert the remaining money back to your currency. Also, there are countries that have restrictions on how much of their currency you are allowed to take out of their country.
You won't be needing to change money as much or as often if you are on a prepaid tour. And whenever possible, it's better to use your credit card or use dollars to pay your bar bills and hotel accommodations.