Even after the modeling was complete (with everything quite polished and very clean geometry and such), I kept designing the color scheme and also tweaked the proportions a bit further using ZBrush and the Move tool. The final mesh can be seen in Fig.06.

Fig. 06
Regarding the last color study, I used keyboard shortcuts to do it, as it gave me a fairly quick way to get good renders and also test using different colors or different materials. Here are some color studies I did (Fig.07).

Fig. 07
Even though I struggled to keep the idea of it having black eyes, it simply wasn't working as well as I'd liked, so I decided to drop this idea and the eyes a glow instead, which ended up being quite cool.
One other detail that I'd also been thinking about since the beginning was also dropped, which was that those wires near the jaw line would serve as veins through which energy or blood would flow around his head. So these would basically glow or have some sort of liquid material, but they were getting way too distracting in the image so I decided to drop the idea and just keep the eyes as the main focus point (Fig.08).

Fig. 08
So everything was set up and then it was time to increase the resolution a lot and render the final image (Fig.09)!
Fig. 09 - Click to Enlarge
Well I hope you guys have liked this little insight into how I created this image and that you might have learned something from it, or at least got some inspiration for your own projects. The reception this image has been getting is being very positive, but everyone is also demanding that I do the full body which I didn't had any plans to in the beginning. However, I am now doing the full body design and hopefully you will see it soon!