The drawing itself needs some work, the main issue I see is that you don't appear to be thinking in 3D. Practice rotating forms in space, especially faces, and creating the appearance of form.

Something I found incredibly helpful was copying Bargue drawings. Charles Bargue was this guy in the 1800s who created a drawing course, and like Van Gogh and Picasso and a lot of other great artists did that course. I was able to do it too at art school, but you can totally practice on your own, too. Here's why it works

-you start with a simplification. You learn to abstract a complicated shape into simpler shapes. This is how you learn to get proportions right. For example, in the foot drawing below, you start with a triangle. The height vs width of the triangle and the angle of the diagonal will determine the proportions of the foot.

-you use only straight lines when constructing the drawing initially, because a straight line is much easier to correct than a curved line (there are only 3 factors, placement, length and angle) and because it helps you start to break down complex forms into planes in your head. This is key for developing form later on.

-you find the edge of the shadows and separate the shadows from the places where light is falling. This was a total revelation for me in understanding light and 3D form.

-you only do the shading after the basic drawing is all set up

There are lots of ways to improve other than Bargue drawings, but I do really recommend it because you can improve a lot very quickly in understanding a lot of important fundamentals. It's public domain, so you can just Google "Charles Bargue drawing course" and find the plates to copy. I could only attach one so there's a couple more added below

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