When preparing to travel overseas, money is a big problem.
Many inexperienced travelers take cash with them, and though that is good to spend at the local airport, it issues arise once in the foreign country.
Using exchange centers is only advisable if one wants to lose a large sum of money, due to outrageous fees and/or poor currency exchange value.
The best course of action is to use credit cards or bank ATM cards.
Though, many websites suggest that not everyone accepts credit cards, for example, small shops, most do.
However, please remember to inform the credit company of the excursion or the card will be decline--if a company knows the card holder lives in the U.S., but then notices the card is being used in Paris, France, it would bring up a flag of fraudulent use.
ATM cards are much easier to use, with machines practically around every corner, sometimes, even two on one street, but, the same rule of telling the bank where you are going still applies.
Trip Advisor claims that the exchange rates you get at ATMs are, in most cases, pretty much the best/same rate as you would get anywhere (that is, when in doubt, use your ATM card to withdraw cash vs. the hassle of doing a "manual" exchange at one of the thousands of such places that do this and they would be correct.
Their other piece of advise of only going to to ATMs of either large foreign institutions like Citibank, or major national banks is also true because some smaller local banks will not allow U.S. card holders to use their machines.
Another thing to keep in mind is the country visited, some have a reputation of being "suspicious" and even with the credit card company or bank knowing your whereabouts, they still won't allow the usage of the card.
According to Trip Advisor, Russia is one of those "suspicious" countries and for those planning to go to the 2014 Winter Olympics in Sochi, be warned that in July, 2011, due to Russia being on that list financial institution (FI) may "block" usage of cards. You many be able to temporarily unblock the injunction. But, at the present time, be forewarned that you will likely find debit card usage to be limited to (PIN-based) ATM withdrawals only, i.e. not good at merchants, or for cash advances. So, for sure, call your FI before you go so you do not encounter any unpleasant surprises!
As for the type of card, Visa and MasterCard are widely accepted, while the use of American Express and/or Discover might cause migraines.