Have a great time! Credit cards are easy to use--the issuing bank will make the conversion on your statement, usually with a small fee ($1-2 US) so where they're accepted I always use it. Not a lot of places take cc's though. Some Pemex (not all), the bigger grocery stores and restaurants. Forget traveler's checks--a thing of the past. Most businesses will take USD, particularly closer to the border, and many places use electronic cash registers that display the price to the operator in both pesos and dollars. I still prefer to pay in pesos as it's their currency and I'm in their country. I try to exchange some dollars for pesos at a Casa de Cambio, they're usually located close to the border on both sides. You'll spot them as they have the current exchange rate posted with bright LED signs in their windows. Then during the trip withdraw pesos as needed from bank atm's. Atm's can be hard to find, usually only in the larger towns and cities, and there will always be a small fee, around $5 US for each transaction. I believe that in Mexico, atm card PINs must be 4 digits. I can't say for certain, but while still in the US I changed my card PIN to a 4 digit code just in case. No problems using it. You need to spend a little time planning your cash supplies mostly because of the scarcity of banks/atm's.