You probably want to spend more time making games than playing them, especially if you're practicing, trying to get in. Unless your a designer and you're playing to figure out mechanics or something, playing games is a bit of a time sink.
Are you an artist? If so, then basically what everyone's said already - hard work and practice. There honestly isn't much more to it than that, besides having the proper skills and understanding of color, light, surface properties and other art disciplines. You can probably find a few quick tutorials on how to do painted…