I've never really done a layout to show how a design progresses from the very beginning thumbnail sketch to the end so I figured I would do one to show some process.
1. Starting off with a quick pencil sketch that gets scanned in and then modified a little bit in photoshop to fill out the space of the design with background.
2. Basic color comp to get a feel for values and the basic structure for all the parts. These colors are placed on a layer below the linework with the lines being made into a multiply layer.
3. A lot of rendering between the two steps here, mostly going from piece to piece and maintaining separate layers for different parts (the face is under the hair layer, hair is under the hood layer, etc.) to simplify painting overlaps between areas. All of the rendered layers exist over top of the linework multiply layer and uses the color comp layers as a base layer, so to turn that off would leave some gaps. Background gets a bit more fleshed out and the ideas for the texture get started for an area. The rendering is often the longest phase, taking about 20 hours to complete painting in all the details. A lot of the anatomy adjustment happens at this step where bits are cut and rotated or shifted after flipping the canvas horizontal and then back to see the composition fresh. Once the area looks more accurate it gets rendered out.
4. To finalize there are subtle multiply layers placed on the figure to enhance the shadowed areas and give them more depth. They are really low opacity layers painted out with a low opacity soft brush to add additional curvature and a bit of color to shadow areas. The background rendering gets finished and bloom layers are added to edges catching light. Whatever other final touch layers need to be added in are added. Again, a lot of rendering that really eats up the time after all the planning phase is done.