Probably the only comments you will get right now are about the format you used for saving.
Don't save as .jpg as it adds noise and defeats of the pixel precision you are meant to have with pixel art, so next time save as .png or .gif.
Also what you have posted hasn't been treated on a pixel level. It is closer to Oekaki more than anything.
Just making some lines with the vector tools, "paint-bucketing" them with colors and adding the shading the same way, doesn't always qualify as pixel art.
It seems you haven't even zoomed once, there are broken lines here and there, and parts left uncolored.
I know it is a first try, but I guess it will be better to set things straight from the beginning, esp. if you want to get into this.
Pixel art isn't just about bitmap images without automatic AA.
In pixel art you have to take control of every pixel, as every single one can add information to your picture (which means ideally you have to push them yourself onto the canvas).
You have to make the most with the least.
It will be way more tedious than simply using the vector tools, but well, that's the way it is (as it pretty much is the evolution of what people came up with to do art while fighting old computer restrictions)
But enough talking I guess.
You could start by reading some tutorials to guide you or something.
You can find some here:
http://www.wayofthepixel.net/pixelation/index.php?topic=3467.0Good luck with further tries.