Heh, yeah. That happens too. Though personally I prefer fighting with something to the bitter end rather than outright scrapping it, in most circumstances. The face wasn't too bad overall, so it could've been preserved.

There are many considerations for shading, but for the most part I just learn by experience and example. I also use cross-field experience, like the ambient occlusion I'd picked up from 3D modelling. Basically, the more a point of a surface is surrounded by opaque objects, the darker it's going to be. It's sort of hard to explain and examplify, for me at least. I don't even have any tutorial links handy. Maybe Thanqol will pop back in with some.

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New thing today, re-rendition of Kira Darkclaw, in mostly pencil.
(Image is screen-stretching, so Link)
If this rate of canvas expansion keeps up, I'll end up in quintuple-digit resolution numbers by autumn. But detail is improving. :D