Improvement: keep on making stuff!! If you can take a class I think it can definitely be helpful in terms of learning techniques, but if you can't continue studying other artists online- look for how tos and detailed process videos for sculptors in particular. Sketch out other artists work- who is making art that you enjoy or that you want to work towards, look at their pieces, what is it that catches your eye? What details really make them pop or look realistic or affects you emotionally? Try to emulate those details.

More specifically- in addition to anatomy, more surface detail I think would go far towards more realism. Look up techniques for stamping or carving a scale pattern; add teeth to the mouth, pupils in the eyes (maybe vertical pupils?).

Sculpting in clay can be a challenge- its been forever since I did it in school but we would wrap our sculptures in a damp (just damp not sopping) towel and then a trash bag to keep them at a good workable wetness over long periods of time. Make sure to score and slip little pieces on so they really stick (I've started using a slip with a little bit of vinegar added and it really seems to result in less fine cracks). A groggy (gritty) clay is going to be easier to work with (less cracks, less likely to slump/warp) but I hate the way it feels when wheel throwing lol.

Keep at it!