I saw that the legs were too short, arms too long, and nya-nya. For some reason it's like you're seeing the picture as if you had just walked up to it. The more time you take, the better it looks. If you get tired of drawing, or something's not right, take a break and come back to it later. Fill up the whole page.
Drawings usually have more impact if their entire area is filled with interesting things.
You usually want to have a main subject, but in the background you can add little things, like if the background's a forest, add a bush or a plant, or if it's a space scene, add a star or a planet or something. Make the picture have something in every corner, to make the viewer have to look around to see it all. The exception to the rule is portraits, or simplistic drawings, or perhaps one where you're using colored paper as a background. Use colors to set moods. That is, if you're doing a color drawing.