For the past year+ I've been gaining more and more interest in doing art assets for video games, particularly classic-style 2D games. I've learned much in that time, and have inevitably produced many pieces that never ended up being used for anything.
As I've no background in any type of animation, over the past year I've invented any number of methods for actually making this kind of thing happen. I use photoshop and its animation window.
My initial method was to simply draw the character model, full color, the way I wanted it to look, then start forcing it. Draw more, frame by frame, without any real plan beyond simple trial and error. I've no interest in traditional animation beyond where it applies to making 2D game art, so my methodology being strange, in itself, doesn't bother me. As a long time art scrapper, first in comics, now in games, I'm more than happy to simple force something to work using my own unorthodox methods.
The most unorthodox is how I started out -- And how I still, in some cases, continue to operate. That is to say, I'll often draw a key pose, cut the character to bits, paste, rotate, distort, and retouch. I'll also sometimes animate body parts (such as the legs) by themselves and add things incrementally. A traditionally trained animator draws things as a whole -- I don't always do that.
Sometimes I do begin by animating a sketch.
But, even when it's a sketch, you can see evidence of how I isolated certain elements. E.g., I didn't add movement (in this case, subtle rotation) to the head until after the fact. This sort of methodology is practical for a untrained animator and, in fact, lends itself well to classic video game motif.
Here's a pretty good example of animating by chopping a character to bits. I simple drew the zombie, cut it into many pieces, and animated them by rotating and moving.
I have some games of my own in the works. More on that later.