Lime green
Well this was notbad i like it to be honest, its a really light feel as is the color, the backround, has really nothing to the visual view, but as for your main drawing here its very "FRESH" looking probably mostly from the light color, now this can still work with some sorta backround you dont have to go all out with some crazy dark stuff but maybe a darker mint green would sufice on the lime green of the drawing, or even a grey backround but even if you didnt go that way you could alsways go with a scenery or backdrop something along them lines
My improving suggestions would be add some sorta backround even if its a solid color that reflects with the main drawing
~X~