Study other peoples artwork to get inspiration, ideas and to pick up some of their strategies and techniques. By study, I don't mean to spend an hour looking at pictures... You need to invest a large number of hours into learning how other people do what they do.
Then spend a lot of time practicing. Draw something rough, improve it a bit, improve it again. Eventually you'll get to the point where you decide it is good, or decide to try something different. I've put about 50 solid hours into drawing my little people sprites, they're still nowhere near finished and I keep changing some part of them slightly every time I look at them. Most art is a process of starting with a base concept and gradually building it up and refining it.