Sorry, but I just don't think you're getting it. Pixelling is drawing.
Pixel Art is just a medium.
Drawing on paper can be art, and pixelling can be art. In the end what you want is good art, and to learn it, you study the fundamentals, and practice them. It applies to any medium you use.
I don't think there's anything wrong with you trying to use the computer to make art as a beginner, although I don't recommend it. I just think it's the fact that you're not really getting it that's getting everyone so worked up and reluctant to help.
Drawing, using a different medium, WILL help you pixel, or make better art.
Now if you mean to say, help me use the strictly pixel-art oriented pixel techniques, (such as dithering, anti-aliasing, etc.) then you should say that, although it's not going to help you make better art, really.
Also, in your above example, when you say you fixed the shading, I don't mean to be rude, but you really didn't, you might be impervious to seeing it as you don't seem to have the knowledge in your fundamentals. It's a good thing though, that you posted in black and white. Leave the detailing, anti-aliasing, for later.
You cat still needs a nose.