I really enjoy your journey thus far. It feels like you have a lot of range and vivid imagination. I also appreciate the fact that your not afraid to explore tough color palettes. Those can sometimes be the most rewarding ones.
Your value scale comes into question for me here and there. I think you could have a wider spectrum of values, which would help you describe your forms in greater detail. This last piece seems to have a solid range of lights to darks. I would encourage you to push it even more in future work.