(Note: I refer to arms/legs/feet etc. to make this easier to read)
Composition: good! No comment there. Color selection and highlight/shadow colors are all fine.
Anatomy-related: given that the bands on the tail have fur-textured edges, the bands on the arms should too, although to a lesser degree. (The little moon marking is fine though.) The extended arm looks a little clunky - it's too thick at the base compared to the other, and doesn't interact with perspective properly. Bending the paw inwards just a little would also give a minor compositional boost.
The toes on the visible foot seem too short - I think the division usually goes back further.
Lineart - your lineart is overall engaging and attractive. However, like the arm vs. tail bands, the lack of cheek fluff in front of the turned-away ear but there on the other is really strange looking. Also, the little line near the armpit of the folded arm doesn't make sense - fur should cover any muscle movement there. Adding a little floof to where the back of the arm joins the body instead would look better.
Consistency of technique: Some people might ding you for using super-shiny eyes, textured background, and fur stylized such that it has no surface texture in the same image. I think it looks pretty great. Might want to make the moon a little lighter, and make sure all the stars come out about round (some are little streaks?)
However... the grass is no good. Treat it just like you treat the fur - give it textural lineart, and don't bring out individual tufts/blades unless it adds visual interest. It's basically like stiff fur.
When drawing grass, pressure sensitivity is NOT your friend - grass blades have pointy tips and taper evenly down the entire length of the blade, not just at the end. Trying to get your brush settings to mimic this is a huge waste of your time. If you feel really strongly about showing individual blades in some spots, using a brush with constant diameter that fades out as you reach the tip is (bizarrely) more convincing looking.
This may sting a little. As consolation, I suggest looking at some of my older pieces...androidarts.com/art_tut.htm
is very relevant, even though it's not geared towards cell-type shading methods.
1. Where is the light coming from
The moon? The moon and some other thing? We just don't know. The extended leg and the specular highlights in the eyes imply a bright light source forward-left side-above the center of the image, but this isn't shown elsewhere on the fur. This brings us to...
2. What shape is this cat
Shadows and highlights, *especially* in stylized but anatomically lifelike techniques like this one, give us our impression of dimensionality.
As is, most of the cat looks like a slightly folded cardboard cutout.
This is very difficult to explain by text. I learned how to do this by doing studies of sculptures and stuffed animals lit from the appropriate directions. This is basically the only way to learn it, unfortunately. The above link will probably be helpful.
The softness of the highlights is fine, but their placement is not.
3. Specular highlights on fur
...should always follow the direction of the hair shafts, not the contour of the body!!! There is nothing to make a sharp reflection there! Especially if (like the visible foot) there's something between the light source and the surface! This goes along with part 2, but it's what made me notice the shading issues in the first place. Leave the speculars off entirely; it'll mask other shading vagaries while you work the underlying kinks out.
Wow, am I pedantic. Grass. Anyway, leaves are translucent. The color you see when a leaf is between you and the direction of the light source will be a more saturated yellow-green. The more blueish highlights are usually reflections of the blue sky. The more you know.
Anyway, my overall feeling is that you're already most of the way to making REALLY awesome art. Your lineart speaks to an understanding of the shapes you're trying to show, and your overall visual idea is good, you just need to work on showing forms.