At first glance this doesn't look too bad...
On second glance there's a bunch of stuff that needs correcting/improving.

First things first... if you color your artworks; keep the lineart and the colors on separate layers, keep the lineart on top and set it to "multiply" or whatever equivalent your art program has.

That way you won't get those ugly white borderlines.

Speaking of lines... for the... guitar strings you should have used a line tool to ensure that the lines would be straight.

The eyebrows could be thicker.

Some small but necessary details are missing; the strap of the guitar/banjo, the left thumb