Let’s practice how to One Line Drawing Hand and Butterfly. The fingers have perfect proportions in terms of thickness, length, and palm of the hand. This takes a long time to practice. Especially as a beginner.
My work is a bit small in proportion to the palm of my hand and my fingers are not perfectly proportioned.
You can refer to it.
Finally, I put together a video of the exercise process. I hope it can give you some inspiration.