You're getting closer. Just make the shading colors darker, while leaving the base colors of the sprite alone (the colors that are not part of the shading or highlights).
The same goes for the highlights, but make them brighter instead. Also, don't forget about desaturating the shading and highlight colors and get in there with your hue shifting.
The same goes for the highlights, but make them brighter instead. Also, don't forget about desaturating the shading and highlight colors and get in there with your hue shifting.