When changing cash or travellers cheques you will usually find the best exchange rates in a ?Casa de Cambio?. The other option is to use any of the major banks but in the larger cities only the head offices offer an exchange facility. It is also worth noting that the foreign exchange departments often close at 1pm, although some do remain open until 2pm or 3pm. Certain branches will only change a minimum of US$100 while others impose a fee of $20 no matter how large or small the amount being changed. Therefore, it is worth looking around before exchanging any foreign cash. US dollars are the most convenient currency to change.
Credit cards and bank cards can be used at ATMs to withdraw cash, once they show the Cirrus symbol and credit card logos.
I personally used only my ATM card with the visa symbol. While I couldn't use it at every location, it worked well enough. (Before going to smaller cities, make sure you have enough cash to get around and a little cushion)

