Now, it's important that you know the focal points of paws, since they are the main weapons of battle for felines. Typically, the two middle paw toes are the largest toes on the entire paw. The claws will be similar in size though. Another thing is that, when paws are spanned upon a surface, their toes will flesh out, and become box-like. Here I sort of exaggerated the boxy look, just because that's part of cartooning, and it also intensifies the feel, unlike realism. I would recommend studying and observing as much as you can, as it will seriously aid you in the future. References are your friends, use them at your leisure.