This achievement can easily be obtained on the first chapter of the first level.
Locations for Chapter 1 posters:
- The first poster is where you drop down into a room at the very beginning, the game will tell you about posters, it should be on the wall right in front of you.
- The second poster is to your left as you cooperate with your G-Unit ally to open the shutters
- The third poster is to your right after the cutscene around the corner from the second poster.
- The fourth poster is in an alcove behind you after you cross the scaffold and the building and perform a coop move with your G-Unit ally.
- The fifth poster is in a secret alcove boarded with wood. You drop down from the room at the end of the hallway which is accessed by the bridge that is hit by a mortar, after the cutscene break the wood that is blocking the room and then break the wood of the secret area to your left.