Thanks again~ 

This time remade hair, fiddling around with fiber material, but still wont look as good without soften shader. 
Planning to use maya or using blender with hairnet plugin. Former option is better with lots of tutorials, but have to learn another software....again. 

Thanks, but I have to pause my work in 3D, as there are many works to do lately. So I didn't get to play around with hairnet. Sorry

Not sure, but you can find it online *cough*free*cough*

But yeah, for reference, look at azarimy's doodling over the years here or this guy's doodling.
htps://forum.lowyat.net/topic/3736293

Apart from the cartoony style doodles, you'd want to easily draw something of that caliber on your own.
You need that freedom, and doodling cartoon or semi-realistic figure is the way to gain it quickly.

You need to develop that carefree strokes.
This trains your visualization skill, constructing a shape in your head and being able to draw it with your hand as accurate and efficient as possible with practice.

Form and flow first, put aside accuracy, style preference or aesthetics much later.



Don't jump straight to learning how to draw pretty stuff.. you'll pick up lots of bad practice and really hard to unlearn it..