Look at the early XKCD comics, and you'll realise that the artist honed his skill over time. There's no secret to being a good comic book artist – it's just a love of the medium and a slavish commitment to draw as much as humanly possible.

drawing is a technical skill. No mystery or magic behind what anyone's doing. The nature of perspective and color won't change. If you want to draw humans, the basics of human anatomy and proportions are pretty constant and have been analyzed to death; add anything else you're interested in drawing and the same can likely be said for anything from wildlife, plantlife, machinery, buildings, vehicles, etc. You can learn to draw just like you can learn to add and subtract.

Just do it.

I don't consider myself artistic, but for a few months in college took up sketching and found I could produce serviceable impressions of still-lifes and even a self portrait, after a fashion. Practice. It works.