Don't rely on just one of these methods to access money. Rather, plan to use a variety of ways so that in case one method does not work, you can fall back on another. In many countries it is possible to use ATM machines to obtain local currency. ATM networks such as Cirrus and Plus seem to be the most widely available. Check with your bank to make sure that your card can be used internationally.
Service charges are usually minimal with bank cards, but considerably higher with credit cards.
Credit cards may also assess interest charges. Where automatic tellers are not yet available, you may charge advances of local currency against a credit card at banks displaying a Visa or MasterCard symbol. Visa, MasterCard, and American Express offer good exchange rates on purchases in many countries and are widely accepted in Europe, Asia, and Latin America. You can generally expect to be able to use credit cards in departments stores, nice restaurants, and hotels. It is suggested that you carry at least two different cards, reserving one for emergencies only.