Jason, I see you've bought the fort from brigademodels. I have used that fort some time for my models.
I painted it always in light brown tones and then I gave it a wash with gray ink. Finally a dry brush for all corners.
I would have liked that brigademodels had textured the walls. The walls are smooth and monotonous, but it does not mean that it is a good piece of modeling.

When I have some time I have to finish the ravelins of my fort that I know Rob is waiting for