>>1976I guess just pointing out the things that stick out to me the most:
*The colors are unappealing. Bright yellow is usually a bad choice for a background, since it pops out and takes attention away from the subject. And with the head it looks like you added a yellow filter.
*It's lacking structure and form, and looks flat. Especially with the top hat.
*The expression and composure of the character is weird; he's just staring blankly with fish eyes, frowning.
* Composition is also bad. The character's body is on the right side of the drawing, in a way that is neither symmetrical nor follows the Rule of Thirds. Worse, his shoulder is tangent with the pictorial plane (the edge of the picture.)
And yeah, besides that it's just lacking in all the fundamentals like I said. But you're a beginner, so like I said, just keep at it. I hope that helps!