How can I learn to make pixel art?

The strongest beginner's introduction to pixel art that I've seen is by Derek Yu: http://www.derekyu.com/?page_id=218 It's roughly the same process you learn when doing conventional illustration or painting: start with a loose line drawing, fill in shapes of color, add detail. Derek gives a great outline of the overall process. Going deeper, there are much more specific challenges in pixel art like isometric perspectives and sprite animation. This site has links to a bunch of different tutorials that cover topics like these: http://gas13.ru/v3/tutorials/ Finally, I'd recommend studying the games you like. You'll discover all sorts of weird quirks to doing pixel art. Lines won't quite connect the way you hope, colors will have unexpected effects on each other. The great pixel artists have solutions for these problems, especially in the older games where they were working in very tight graphical constraints.

Two side notes to David's answer -- I'm sufficiently dense to have not understood the tutorials on how the isometric cube works at the pixel level, so here's a mini-demo of the isometric he mentioned, with the basic cube on the left, and clones on the right. For scenes with multiple elements, a grid can make it easier to line things up, you can always delete it later: Also remember that things that look good in pixel art sometimes look pretty bad close up, don't let your eyes fool you. Here's the a pixel art guitar pedal and a blow up of the jack: