I recently completed a little style test for a horror project. The client was looking to find a way to stylize the look of their creature and make it more graphic, but also include the photo realism that a more contemporary audience is looking for. That's like two extreme opposites in styles right? But this is the same challenge that Sin City tackled. Our client was a big fan of Bernie Wrightson (blow mind away here), and as a proof of concept, I was tasked to create a photo real version of the below pen and ink, the results of which might be used to inform the visual style for the project's own creature.
I kept an overlay of the pen and ink for a long time before I modified them a little to make a more realistically lit character. It's anyone's guess as to what swampy materials were originally intended for the character, so I just did my best with lots of moss and roots. I tried to find a lot of things that would feel like body tissues and exposed nervous systems.