This image used airbrushing. Lots and lots of airbrushing. As well as Burn, Dodge, and gradients.
This was all to keep within the Art Nouveau style, which, though graphic, employed careful washes and gradient colors to avoid detracting from the linework. I was also trying to employ a visual break from my usual style to emphasize the difference.
If it’s any help, the Zelda pic did employ the original steps in the tutorial, including the linework and blocking base colors. The only real difference was applying washes of shadow colors, rather than clean-cut sections. The additional shading and highlighting was done in the same Dodge/Burn fashion as in the original tutorial.
Hope that helps!