Success! (...I think.) The Otherworld trolls are done. It took longer than anticipated and maybe I should have done a few things differently but I'm happy with how they turned out. Pictures can be found here.
As for my "make it up as I go along" painting technique, I convinced myself that large scale drybrushing could produce satisfactory results despite all evidence to the contrary. In the end I may have been right, but a lot of glazing was required to soften the harshness of the drybrushing.
I took pictures as I went along. The first step, black undercoat:
Next, dark green basecoat:
Drybrushed with progressively lighter tones all the way up to straight yellow:
Green & yellow ink wash:
More drybrushing, this time taking it all the way to white:
More ink, a lighter application this time:
Extensive glazing with Scorpion Green (GW) in an attempt to tie everything together:
Some glazing with Golden Flesh (Reaper) and Warlock Purple (GW):