Heh, there's tons of different types to create an animation.
Thanks to the invention of the compture, animators have found a great short-cut, "tweening."
Programs like Flash or most 3-d creation softwares, will automatically "tween" for you. Essentially, it will take a frame of a character in pose A and the guess what needs to move to reach pose B. Normally, the tweening needs a lot of tweaking to it, because the transition is very direct and unnatural, but still very effective.
If you want to go the longer way, but a lot more control you can draw pose A and then pose B ... after all of that, go through and individually make a frame in-between the poses. That's old school animation for you right there
But that's probably done best with a light table (a table that's effectively a giant light so you can see the page below the one you're drawing on -- to make sure everything lines up right).
So, the answer to your question revolves around another couple of questions.
Do you want to do 3-d animation or 2-d?
Do you want to use a program or do you want to do it all by hand?
My suggestion would try to make a flipbook first, just to see how you do with it. Scan them in and make it into an animated .gif
Then, after you got that down, you'll start recognizing basic poses, the moments where the character's arm stops moving one way and begins another -- my prof.s called them the extreme poses.
After a couple of flipbooks, try your hand with a program, but there's always a learning curve with whatever program you choose. I can't think of one where you can just sit down and the "tweening" is super quick and easy to learn. And even though I have great love for Flash, sometimes the math it does can go horribly wrong.
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