stepl
Line work: draw a rough line work with a pencil and spread the background color.
Second step
Dark part: add the color of the picture, pay attention to the true and false color and the direction of light.
Third step
Thinning: Blur the mixed colors with Meidi Kose, and don't pull the value too high.
Fourth step
Highlight: the opposite direction of light, plus highlights and shadows.
Step five
Finally, brighten the shadow and soften the picture with a soft-edged brush to make the water droplets more realistic.