This is a pretty fun little monster, I might have gone a bit overboard playing with it, a bit beholder-y, anyhow:
Your colours were kinda monotone (at least more particularly in v2 which I had saved to work on
); as long as you keep the local colour (as uninfluenced by lighting) around the middle of the ramp you can retain the impression of it being red…without everything being red. I desaturated my lows ‘cos less light = less colour and moved towards yellow in the highs ‘cos that’s a nice fiery look, and so they don’t have to be ultra-saturated in order to contrast (yellow being inherently lighter than red) while adding white would lose colour identity and look drab.
I think the issue with detail is as much the bit shapeless/awkward monster design as lack of space for relevant stuff. I dunno how the painted ref. is related to what you’re doing but it leans quite heavily on those omni-rimlights to be understood which I think would be a major pain as an animated sprite, the tentacle-things flatten/unbalances stuff in their current position (also tangent on the farmost) and the yellow wing tips distract from the glowing mouth; are they glowing too?
Gotta reiterate quickly what’s been said on form already; looks like you’re flood filling black linework rather than shading and I’m sure this has been mentioned before for stuff you've posted. You could really do with practising simple volumes/contrasts without lines and sketch stuff out as rough geometric primitives (boxes, spheres) before starting details or specifics.
