Kill the background.
Way too many dark shades. How many colors are you using for outlines?
Push your palette around more. Look at how many colors you're using for the mouth. How many of those colors aren't used anywhere else?
If you REALLY want that "cartoony outlines" look, still try to aa the lines, or at least use lighter shades for the lines depending on where the light falls.
The character's design is really boring. With the exception of the cigarette, there's nothing about the face that sticks out. Maybe add a nose (assuming that spike coming from his cheek is just that; a spike)? Some pupils? Ear openings? Eyebrows? Add some detail to that sword's sheath, man.
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Your design w/o a background.
AA more effectively / maximize use of your colors. (Eye / Sword handle)
More details? Give your character MORE character. (Nose and pupils)
Work on being more patient.