Credit cards are a great resource for getting out of emergency situations. It is a good idea to carry a MasterCard, Visa, or American Express credit card. You should contact your credit card company to find out the fees associated with withdrawing funds, and to let them know the duration of your trip abroad. If your card is used overseas without prior notification the account may be inaccessible for security reasonsContact your bank to ensure that your ATM card and credit card will work abroad, and whether there are additional fees. It may be necessary to notify your bank that you'll be using your cards abroad to avoid having them locked for security.
Consider carrying some U.S. and local currency, especially on the days that you are entering and departing from various destinations. It is important never to carry large quantities of cash.
Investigate exchange rates between U.S. dollars and the currency used by your host country. Googling "exchange rates" calls up a convenient currency conversion tool.