For one: try drawing with thinner lines, or it'll look too sloppy. For two: try drawing with shapes, they help a lot when drawing. For three: Use something OTHER then MS Paint. I suggest Photoshop, it's an awesome program with a lot of cool things (though Paint is good for beginners). One final suggestion I have; is to not use too many dark or light colors. Colors too dark will make it hard to see the lines or other areas, and too light will blind the viewer. Also, try drawing slowly, and since you're a beginner, I suggest using pixels first. Drawing pixel by pixel is how you sprite, and spriting is a key helper to learning to do computer art. Finally; DO NOT USE SPRAY PAINT! Spray paint makes it hard to see and ruins the quality, also, it's crap.
There, I hope that helps you.
For anymore help, ask Spar, she's an excellent artist. 
