You have a tendency to ignore mid-level details like proper depiction of form. You seem to habitually do the big shapes, then the micro details, and don’t spend enough time on thinking about the forms.
For creatures, the anatomy has to appear convincing. so study the anatomy of different animal types and incorporate them into your visual vocabulary when you design creatures. Also, the surface property is also very important such as scales, textures, specularity, etc. Study everything from mammals to deep sea creatures to insects to reptiles.
I don’t know what your aspirations are as an artist, but assuming you are professional aspirations, I would suggest you buckle down and study the critical foundations of visual art, and start doing it seriously before you build up too many bad habits that you’re going to have to unlearn later in your artistic development. If you haven’t done so, head on over to the Art T&T subforum (linked below in my signature) and read the sticky threads–it’s created for people who want to excel effectively as artists.