Teefury

P.s.s: The pose for marceline isn't 100% original, i had to use a reference pic-just felt like that should be out there

As far as a color scheme, Marceline is made up of a pretty muted palette . Useless you're going for a different vibe, it's still to early to tell.

I'd change your white to a light grey maybe with a hint of purple if you are using that as a skin tone.

Maybe have the ax the same color as her belt. You could use that for the mouth/shoes ect.

I was thinking of having mostly composed of purple hues. something like this quick selection I made on colorblender.com. I toy around with that a lot cause color theory has never been my strong suit.