The Big Con

You can earn this achievement in Las Venganza when Myrna asks you to find 5 out of state driver's licenses for her.

In my playthrough, she appeared outside of the Rusted Springs building after I stole the shoes for Sneaky Dee and Jimmy. This is where she gives you the objective. From here, just go around pickpocketing random people until you find at least 5 out of state licenses (I had 7 or 8 licenses before speaking to her so I'm not sure if you need more than 5 licenses for the achievement so I recommend grabbing a few extras just to be safe). Once you have at least 5, go find Myrna outside of the Rusted Springs and talk to her. She will tell you she's impressed and give information to progress the main quest line.

After the conversation ends, the achievement will unlock