When working with line weight, you need to give thought to why you are using thick and thin lines in specific areas. Line weight can describe so much, if you know how to use it–and it’s not arbitrary.
You can use thicker lines to convey heavier objects, or objects that are closer to the viewer, or objects with larger mass (and thin lines for the opposite). It’s also a good idea to go thicker on areas where the contour is concave, and thinner on areas that are convex (such as how the lower leg flares out (convex) and the ankles taper in (convex).
If you apply these principles to your line work, your line art will become a lot more coherent, as well as expressive in a way that makes sense.
As for the painting aspect, you have an inconsistent usage of brushwork, where there’s sharp bristle marks, smudgy brushwork, and streaky strokes in random areas without any reasons behind them. Brushwork isn’t arbitrary–there are specific reasons to deploy certain brushwork to certain areas. You can convey the surface property by using different brushwork, and you can create visual interest by using your brushwork to bring attention to focal areas.
Also, messy is not the same thing as expressive. Messy is when someone who doesn’t know why he’s painting the way he does tries to be expressive, and expressiveness is when someone with skill and knowledge deploys specific types of brushwork to create exactly the kind of artistic sensibility he’s going for, and it is done with precision, despite how expressive it looks. Brush economy, speed, and arbitrary messiness is not the same thing as skillful expressiveness.