1. First we have the line art, is the most important, you must work in the scketch and work in anatomy and perspective...
The lines are from bosstones22 [link]

2. I use to work with photoshop for the inks, you have to modify the brush, use a normal brush 19 and in brush presets mark Shape dinamics (size jitter->en pressure, angle jitter->en pressure), other dinamics(flow jitter->en pressure) and smoothing. Is very important that you use a wacom intuos because it have more presion ponints that a graphire... You have to make quick and precise movements, if you make mistakes control+z or erase are your friends...

3. I make a new layer and color with basics colors.

4. Shadows: Make another layer in mode multiply, decrease the opacity and the fill (50% + -) and make shadows with the brush and 100% black, then we can colorize it in layers->layer style->color overlay, decrease the opacity and select a color.

5. make the background, is better to make it first to see how affects the spot lights and the sadows in the scene.

I have make what I can... sorry for my english