Hangar
On the second floor of the hangar is a small room. From the outside, you can get to it by climbing up the rubble pile on the side of the building.
Go to the porch outside the hanger entrance. Close to the hanger is a large white carved stone. Jump on it, and try and hop over the fence. You will fail, but will land on the fence.
Makin
Go to the circular building, and look through the stair entrance. There should be a hut with two rectangular windows overlooking the sandy area that can be used as a sniper position. Also, there is a tall building on the water with windows overlooking the entire map that can be used.
Outskirts
Once inside the church tower, look through the circular window. There is a white building with a small balcony in the distance. Use it to snipe from.
Roundhouse
There is a platform/hallway that goes over the middle of the map. To get to it, go behind the trashed locomotives. Climb up the staircase, and turn left at the round platform. You should have a good view of the whole roundhouse in the middle of the map.
Upheaval
Towards the top of the map is building with two windows that overlook the whole area. Note: Other players will try to get you.
Go into the house next to the burning house. Stand on a windowsill, and face the side. You should fall on a ledge below.
Enter the burning house. Go up the steps and out the window in the same way to hit a ledge below.