I've split it up into zones, and put a number so you can see. :3
1 - the head.
Size: The head should be smaller than the chest, if you're going for a realistic cat.
Of course, if you're looking for a more cartoonish cat, it doesn't matter as much.Facial Structure: Cats don't have a long snout like canines. It's actually quite short, and blends smoothly into the rest of the face.
Neck: Cats have fairly short, thick necks.
2 - Shoulders and chest
Shoulder: You did a good job of the shoulder. ^u^ Just needs to be a little more sloped, is all. I did a fairly simplified oval shape, just to get the gist of the angles, but you can also use a triangle.
Chest: Unless they are extremely fluffy, a cat's chest doesn't puff out beyond the point of shoulder.
3 - Back and Stomach
Back - Most of the time, a cat's back is slightly arched.
Stomach - You did a good job of this! Many people tend to "tuck up" the stomach, like in a canine, but a cat's stomach is normally pretty flat along the bottom, or even thicker towards the back end.
4 - Back legs/Hip
Just remember that the leg attaches at the hip, which is at the top of the cat. This means that it is more of a long triangular/oval, and not circle.
Also, the angle of the "knee" at the back is a little too sharp - the "knee" of the back leg is actually the same joint as our heel. Basically, a cat walks around on it's toes.
So basically, just lengthen the space between the body/hip area, and that heel.
5 - Tail
There wasn't really anything much wrong with your tail. All that I would say, is perhaps attach it a little farther back.
6 - Back paws
Normally when a cat stands, it's legs don't go straight up and down - sometimes they do, but more often they're angled a bit. :3
7 - Front Paws
Just remember to show the wrist joint.
I hope this helps! It might not be 100% accurate, because I just did it quickly and without an exact reference. I would suggest using reference images when drawing cats, to really get your anatomy down. :3 Let me know if you have any questions.
