A decent start. Inspecting it closely, I can see that it looks like you used a paint bucket tool to color it, which leaves these tiny white outlines between the color and the line art.
If you have access to layers in your drawing program, I would suggest painting the color by hand with a brush instead. If you don't have layers, you can try making the basic shapes in color first and then adding the line art on top.
Speaking of line art, line width variation will make it more appealing. A lot of the lines in this picture are extremely thick. I would suggest using smaller lines for smaller details or things closer to the inside of the drawing and use thick lines to separate distinct parts of the subject.
Sorry if I came off as preachy, this really is a good start! The mask design itself is very appealing, and the hat is a nice touch!