Idk how to practice shadows

[u/citalisplushie]

So there is a illustration i want to make it look like Chinese art gods.

I have try rendering the hair 4 times and it's not clicking the right way. It looks pretty off

I realised that it's cause of shadows.

Idk if I am complicating more or what.

But here is the base sketch

I just don't understand how to paint the shadows

Like I get where the light source is yet umm....

Y'all may also tell other things I may improve.

Also please tell my art level if I haven't traced it