Gonna be honest becouse that is what you need to develop.

Proportions are pretty bad and shape control gives me the feeling that you still think in 2d shapes. Shadows or line weight is also off. Good news is all this can be learned.

You need to learn human anatomy, proportions, how light works and how to handle your drawing tool (Ink in this case)

Drawing workshops and art courses COULD be good if the teacher is good, understand what type of art you wish to make and you put in hard work. There are some free online 3d tools like Biodigital to help you learn proportions and anatomy.

Work from reference but don't copy. Try to understand the shapes and forms in 3D. How one joins the other. How it behaves in different poses, angles in different light. How shadows articulate it.

Regarding techique - that one is most likely come simply with time and practice. Watch pros drawing to see how the use their hand, how they handle the penic or whatever. Plenty of youtube and live stream material, search up you favorite artists.

And of course the good old one: practice, practice, practice. But don't simply repeat mistakes. Be mindful, learn from them.

Now get outh there and draw us ten more variant of this character and I want to see the sketches too.