It's a challenge to manage your values when most of the image is in shadow, if they get too close, the depth goes out the window, if they get too contrasty, there's no range left for the lit areas!

You can find more of my work at:
http://syncup.deviantart.com/ and https://torewesolowskidesign.artstation.com/
にほんごもだいじょうぶです。