Thank you Wayuki ! Your advice is really helpful, I'll try it on the next drawing

As a general rule, shifting your shadows towards purple should work quite well. But it depends on the lighting, really. The shadows are tinted by colors bouncing around in the environment. Hue-shifting towards a blueish tint often looks good, because the sky is the main light source tinting the shadows in outdoor scenes. But in indoor scenes, the shadows are more likely going to be warm.

Oh thank you ! As I understand, the darker color of the hair should be hue-shifted to purple, isn't it ?

Nice work, but the palettes could benefit from some more hue-shifting.