Hey! Cool stuff keep drawing. I think you are doing a fine job so far and with practice just like any other artist in the world can and will become much better!
My suggestion is doing studies. A study is where you take a particular object or area of art and draw that and that only very intensely. Just pick something like. Texture,Shading,Figure,Form,Gestures etc etc etc. Or you can be specific and do studies on lions,tigers,roads,gravel,sand,etc etc etc. These studies will help you develop the techniques and understandings of how things should and will be portrayed on paper.
Doing realism is helpful even if your a cartoonist. Simply because people associate there views on your work based off things they see on a regular basis. So if someone see's people on a regular basis you need to implement familiar features from people into your work (if they are meant to resemble people) that way they can appreciate it better and further understand your artistic abilities. Same can be applied with just about anything.
When it comes to understanding fur or eyes. Sit down one day or maybe for 2 weeks do nothing but drawing fur and eyes. Do HIGHLY detailed drawings to not so detailed drawings. Then keep repeating the process until you are satisfied. This is how artists learn this is how we develop.
Keep practicing it takes time.