I remember coming across a quote while doing some research online for something else. It was along the lines of "Art is 60% patience, 30% determination and 10% skill". I can't remember exactly what the 30% bit was but you get the idea, skill has very little to do with a piece of art.
Though some may disagree, in my personal experience the thing I lack, and hate most about myself, is the patience to really finish off a piece or fix the broken bits in a picture. I just plain can't be bothered to tidy up an image. It also doesn't help that I prefer sketchy stuff and usually loath rendering in an image.
One friend of mine from college is a perfect example of patience. Over the three years I knew him he progressed greatly in his work. To cut a long story short, what impressed me was his patience to stick with a painting he was doing. He made up for his lack of skill with sheer willpower.
If you're interested in MS Paint tutorials I'd recommend looking on DeviantArt.
Here's a link to a quick search result of stuff.