[Random Art browsing review!] The design and expression is really cute! However, the dark tones used in the skin, hair and text combined with the thick lineart makes the points of interest (the face) very heavy and overwhelming to the eye! This is accentuated by the very light unsaturated colors in the background and shirt. Also the fact that the shirt is of a neutral light grey brings unnecessary attention to it.
IMO, to fix that you could have used a warmer, just a tiny bit darker color for the shirt so all colors were in harmony with each other. Maybe also using a lighter color for the skin, or darkening/unsaturating the background so the skin looks brighter in comparision.