There are 8 posters total hidden in various spots. In order to get the achievement, you must find all of them and complete the heist.

The first poster can be found right around the corner behind your spawn point.

The second poster is on a wall left of the car wreck of your escape driver Eddie. When you reach the crashed car head left.

Continue down the street to reach the construction with the yellow crane. To your right side, there will be wooden boardsalong a scaffolding. At the far corner of these will be the third poster.

Continue past the yellow crane and the SWAT van on the left sidewalk, past the hotdog stand there's a billboard. On the other side of that billboard you will find the fourth poster.

From the fourth poster, cross the street. On the other side you will find newspaper boxes to the right of the entrance to the parking lot. the fifth poster can be found on the side of the boxes that is facing the intersection.

The sixth poster is just a bit further ahead towards the crash site. On the right side there's a SWAT van that has crashed into a plant pot. To the right of that is the poster on a wall.

Continue with the mission and get Matt out of the van and through the alleyways up to the overpass. Just after you come up the stairs that lead to the upper street, turn right. The seventh poster is just to the right of the storefront of "Ivan's Pizza".

The eighth and final poster can be found at the very top of the hill where Bile picks you up.
Move all the way up to the barriers at the top. The poster is on plant pot that is the closest to the police barriers and the blue dumpster on the righthand side. (This poster may sometimes be invisible but you will still be able to interact with it.)