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I'm not a good spriter myself, but I think the outline of the hair needs to be the one that has a dark pallette and clothes might need shading, cause it only has one color currently, but maybe it's just me tho. ^^
Well just as hellhound pointed out the sprite need shading
also I see on the back of the sprite you tried to create highlight...
It is way to dark, at the normal sized sprite you can't even see it, I would not recommand to use black by the way. Try to use darker blue instead ^^