Especially the artwork!
In the first volume there was a mini tutorial. I decided to try the technique on an old sketch:

The first and most important step: Create clean lineart!
Since I normally don’t do this, it took me a rather long time. But spending time and effort on this will make life easier in the following steps.

Next I worked on the background. I had reference material for the flames which helped a lot when it came to picking the appropriate colors. The fire was painted with different standard brushes and a low value for “Flow”.

According to the tutorial, I picked the darkest color from the background and filled my lineart with it:

Not bad, but this led to the next problem: How much color could/should be visible on the characters?
This time I tried something I learned in the digitalartforum: Treat coloring and shading as different problems.
So I did the shading with only one color on one layer. On top of it I had another layer on which I only painted the colors without any shading.
The color layer got the blending mode “Color dodge” and 50 % opacity. Now it looked like this:

Almost there! Some work on the metal parts and some highlights and I call it done:

I’m quite satisfied with the result. Having such a structured work flow was very helpful for me.
Maybe it is for you, too :)