Process started with a pencil sketch, then scanned into Photoshop. Using a couple of Levels adjustment layers, I tweaked the paper background back to 50% and erased parts of the layers to create a tonal painting effect. Overlayed a monotone color layer and finished off with several photo textures taken myself from various decaying household items. The blotchy effect here was from spilling coffee over vellum bristol and letting it dry with the grounds scattered on top.
Wow that is a lot of technically stuff going on behind the artwork. And it paid off for you. I've only barely started fiddling with digital art again. Do you have any existing tutorials with that?