@Josiah VE, I used Photoshop for the linework with a pressure sensitive tablet.
I have a pencil brush preset I picked up somewhere, can't remember exactly but there are tons out there. Tweaked that one a bit to grunge it up and used it for the linework.
For the colors I experimented with a few different brushes, but most was done with a soft-edge circular brush with pressure width, ink flow, and opacity. It let me vary from super thin and light to very wide solid marks without a lot of brush switching.