Changing currency from your national flavor to the Peso is nothing that you need any help doing. However, there are easier ways to exchange money than going to the local bank and waiting in line (sometimes for an hour) to cash travelers checks or to trade your currency for Pesos.
To begin with, there is no need to travel with large sums of money on your person whether in your national currency or the Peso.
If you are traveling for any period of a week or more, I would have to recommend against spending money over the International exchange rate day after day to trade currency at a bank or Casa de Cambio. Make no mistake about it . . . banks exist to make a profit and each time you exchange money, they will take their cut. If you bring cash to Mexico, by all means bring the dollar. You will find that other currencies have exchange rates there that are down right insulting.
The safest and easiest way to fund your cash need is to begin with buying some Pesos at your bank before you go.
Next, remember that if you have a charge card, use it whenever possible as the set International currency exchange rate will apply.
For those times when you need some cash . . . remember that you can go to a Walmart, pay with a Visa/Debit card and get some walking around money back. Or, use the ATM.
However, be aware of the ATM scam now popular in some parts of Mexico. This is a high tech form of robbery that will give you plenty of headaches. The crooks (in this case) attach a card reader that looks like it is part of the ATM machine and will copy the magnetic strip on your card when inserted. This is used in combination with a hidden camera that will record your PIN number. Both the data from your magnetic strip and the hidden camera are wirelessly transmitted to a nearby car with a laptop. This information is then used to make an exact duplicate of your card . . . and there are reports of the crooks withdrawing $1500 dollars a day with the duplicate card (Interesting because you could only draw $500 per day).
Protect yourself by only using ATM machines inside banks. Try to use the same machine so that you notice any changes in appearance (particularly over the card reader) . Watch for hidden cameras at an angle to see your PIN number and place one hand over the one you are using to punch in the PIN number (in case there is a hidden camera you don't see).