There's that tutorial, but mostly it'll just take practice and learning to use layers in programs to save yourself some work for things you're likely to re-use. It's difficult to start, and there are times it'll be tough, but you just have to stick with it and eventually you'll start seeing an improvement.
If you're lacking confidence you can start by learning to edit existing sprites and putting them together, and gradually begin to create new parts for new results.
Mostly, though, it just takes a lot of patience. But the tutorials here and in the pixel academy section are good for learning how to do the basics better, especially Tana's for things like giving hair depth.