Anatomy, skin, etc.
deviantART
(may require registration)
skin color tutorial
how to shade skin based on a hand
another great skin color tutorial
basic animal anatomy tutorial
another tutorial on hands
eye drawing tutorial plus references
tutorial that shows the differences of ages on faces
pixiv
(requires registration, Japanese (not necessary though))
hand tutorial
foot tutorial
hand references, also for holding a weapon
hand tutorial with references
hand anatomy tutorial
how to shade skin tutorial
Coloring, styles & co
deviantART
(may require registration)
lesson about colors, effects of different contrasts, etc.
simple hair tutorial (registration required)
how to paint authentic wood
light and shadow shading tutorial
great cell-shading tutorial
a quick tutorial how to paint tree tops
how to shade candy, focuses on light sources, etc.
pixiv
(requires registration, Japanese (not necessary though))
how to paint a blue water orb
how to paint different kinds of brick walls
how to paint rocks, stones, etc.
tree painting tutorial with a lot of Japanese text
how to paint clouds