the studies look really really good!
Some of the colours in your paintings could be improved. You tend to go
with the obvious choice for certain objects. Grass and tress are bright green,
rocks and metal are gray, skin is pinkish beige etc. with shadow and highlight being the same hue & saturation.
You can clearly tell that you already know about translucency and bounce light but you don't always commit to it fully.
I hope you get what I mean^^