What are your preferred methods for carrying around cash in TJ? Up until now, I've just carried cash in different pockets and the bulk of it in a money belt.
Any issues/concerns/problems using the ATMs? Or is that the "safe"/preferred method of pulling cash from the ATM at Cascada/Rizo?


There are ATMs right in Cascadas and Rizo. Usually two side by side, one for Pesos, one for Dollars. The problem with the Dollar dispensing ATMs in the Zona is that they charge a fee of about 15%. So you'll pay $120 to take out the max of $800 USD. Yikes.
So, what many mongers do is get cash in the states and haul their warchest over the border. The belt is a great location for it if your belt can accommodate it.