Near the South Western corner is a building with a ladder going up the back. It is a decent camp spot. I wanted to point out that you can also get up here by climbing the boxes/fence by the transformers and jumping across the transformers to that roof.

Inside the large middle building (great spot); Look for the Forklift. You can go upstairs and fall onto it or start behind the Forklift, look left, go up the 6 steps and jump on top the barrels next to the steps. Jump onto the top of the Forklift, jump onto the barrels in front of the Forklift. Look slightly right at the two 'Compy Corp' white tanks. Jump between them. You now can either go left and be in a dark corner that has a great view of the whole downstairs and one upstairs doorway, with a solid roof protecting you from above, OR you can go right and be in a window overlooking the outside of the building as well as the downstairs, but here you will be seen/able to see people above you so you are more exposed.

Roof on side of middle building; (not great) jump out window onto low roof. Or, from the ground; find the 'container' next to the roof. Jump on the small cement divider at the end of the container, jump to the boxes/tank in green fanced in rectangle, jump from top of tank onto container, jump onto roof.