OP, take the time to properly setup a nice Startup file with a basic 3 point lighting setup, a couple generic HDRIs, some materials you use all the time (diffuse + glossy fresnel mix, or Cynikatpro's really nice materials), and so on.
Anyway, as far as the model goes, needs better topology, needs more detail (both wear and tear, as well as character).
Cartoony is good and fine, and low poly is good and fine, but that's no excuse not to bake high poly details into the low poly model. Don't get stuck fixating on the limitations and shortcomings of that era, focus on the style and intent, ask yourself what they'd have done with today's tools to achieve the kind of stylized look they want while still adhering to sensible polygon constraints.
Also, it sounds like you don't have a clear concept in your head and that's tripping you up. You're asking yourself and us questions like 'what color should it be?', well do a sketch and/or compile a bunch of relevant art and pictures, and come up with something.
Keep at it OP, you're doing good.