1. Sketch: This one is not the first sketch I did, its a cleaned one. Once Im happy with the drawing I erase lines here and there to clean it a bit
2. Final Lines: I hate this step, since lines are almost invisible at the end of the piece, I don´t know why the hell I keep doing it. Yeah, Im that dumb. Anyway, as you can see, lines here are even less detailed than in the skecth , specially in the areas that I decide to define with colors (like in the folds of the elbow patch, the mask, belt and so on). I don´t intend to make them look cool or great, they are more a guide than anything else.
3. Flats: Not much to say. I try to be careful with the color filling, because line´s opacity is very low, and they take the colors of the layer below. I also hate this step.
4. Shades: Now we are talking! This is FUN! Several layers in multiply mode. Painted them with the regular soft and hard photoshop brushes
5. Lights: lots of layers in different blending modes: overlay (my fav), screen, hard light, etc.. Glowings here and there, and its done. I used the spatter brush, because it gives a nice texture to it
6. Merged layers: This is not a step itself, I just added it to show how the picture looks at this point
7. Textures: I usually don´t texturize my drawings at all. But this one asked for it, so I used different stock textures Ive found around the internet, with veeeery low opacitties, mixing several blending modes. I also added different tones in skin, bandages and leather. I worked this step with lots of different brushes, but again, I mainly used the Spatter brush.
8. Final: BG is pretty simple, it was done very fast. I just painted an overhead light with soft brushes, and used a random sewer pic with super low opacity and a big gaussian blur behind everything. I also did a few color balance tweaks to make Donatello blend with the BG and thats all!
Hope this helps a bit. Feel free to ask anything!