Whoops lots of people have already added to this haha but I think I've got something new to add so might as well! So I did a quick lil redraw:

Just to walk you through some of the things that I did differently:
>The first thing I noticed was the arms! I'm not really too sure if you wanted to do like some foreshortening or something, but in general, the arms are approximately the same length between shoulder and elbow and elbow to fingertip (a lil shorter for the forearm!)
>Next up, the hair! I chose to simplify it a little bit, but a good way to think of hair is in chunks, and when you shade that way, it makes the shapes more distinctive and less visually busy, especially when there's a character with a lot of hair. You always want to make sure that the hair shading looks like it will connect the strands back to the scalp!
>For the body, don't be afraid to give her hips! If you're drawing a female character, they generally tend to be one of the most distinctive features! (even if she's meant to be younger, the structure of her pelvis will still be wider then what you have there - make sure that you're looking at some sort of reference for people)
>In relation to the pelvis, when you widen it the legs will end up in the proper place too. Currently they're tapering too much at the bottom of the skirt in a way that would indicate the crotch would be like right at the bottom of the skirt.
> The ears are a really prominent feature on cat girls! Don't be afraid to exaggerate them more! Personally I like big ears on cat girls, but regardless of what size you draw them at, they should always stand out from the hair in some way (I added a pink inner ear!)
>Almost forgot about this oops, watch the size of your hands! I kind of have a hard time describing the size comparison here, so try and look at reference again!
>Tail position! The shape of your tail looks really good! But you want to make sure it's implied that the connection is at the tailbone/pelvis. In your image you could maybe even have it coming through the hair or something!
>When you're shading a shirt on a character with breasts try not to create too much of a cleft between the boobs! The fabric should sit on top of them, not between them.
>The last thing that I can think of right away is the face shape! Yours is a little too slim. This is another case that reference would be really helpful!
I think overall your colour choice is pretty good! The only thing I really adjusted was the highlight of the hair, which personally i think comes across as more subtle.
That's just my two cents, anyway. Most of the things I'm pointing out are anatomical, and come down to looking at reference when you're working on anatomy! Overall your colour choice for this piece was pretty good, and I like the overall ideas a lot! I think if you just work a little more on the beginning shapes soon you'll have a pretty great cat girl!