Mission 2: Welcome to the Jungle
After leaving the building, head to the dead-end, straight to the south. Find the propaganda poster stuck on a derelict building wall to the southwest. You have to use your nanovisor to download it.
Mission 3: The Root of All Evil
After destroying the dam and being swept by the raging waters, you'll be back on your feet again. Continue forth and you'll get a secondary mission. Check that out first. A short distance after receiving the secondary objective, activate your nanovisor to find the propaganda poster across the gap, in the corner wall.
Mission 4: Safeties Off
After completing the secondary objective, continue forth to your main objective and you'll spot a heavily defended building, beside the chinese structure/arch. There are also collectibles inside. Proceed there and find the propaganda poster in the lower floor, on the wall facing the archway. If you scanned the area, you would have probably tagged and recorded it (a natural occurrence for propaganda posters if you noticed) so if it isn't highlighted in your hud, it's already recorded.
Propaganda Poster, Nanosuit Module Upgrade and Datapad
Mission 5: Red Star Rising
Continue towards the main objective until you run into a grassy area where remaining CELL troops and the ceph are engaged. Be careful of the several stalkers lurking in the area. Make your way to the building to the left and climb the second floor to find another datapad and the propaganda poster in the next room as the datapad.
NY Strike datapad and CELL Bear
Mission 6: Only Human
Continue to the AA battery and find the power source in the building. Destroy it to disable the AAA and have Psycho deal the finishing blow. Check the upper floor of the building to the west, beside the AAA to find a propaganda poster.
Mission 7: Gods and Monsters
As soon as the mission starts, open your nanovisor to tag the collectibles along the way. Right in front of you is the first blackbox of the mission, and a few steps away from it is the propaganda poster.
First few collectibles of the last mission