The app you use is up to you and maybe testing several to find the right one for you is a good idea.
There is no 'secret' to animation other than you should find a way to see the action as frames in your mind as you plan any animation. Use refs, make your own sketches, video action to see movements...whatever it takes.
In pixelart animations sometimes you just imply the action/movement more than actually pixel it.

MSpaint and unFreeze. It ain't, it doesn't need fixin', and I'm too poor/lazy to find something fancy.

So don't feel like you NEED fancy tools to pull it off. They help, but you can get the job done with the bare basics too.

As for the actual process: Trail, error, and learning. Watch a movie, an anime, or just simply play around with toys. Look at them, study them, see how they react. A lot of art isn't the creation of something new, but an imitation of something that already exists.

For me personally animation is the easy part. My biggest challenge is creating the base, Frame 00. Once I get that down the rest is a breeze.



If you break down this animation for analysis it's very simplistic. There was absolutely nothing hard about any of the individual steps. One minor edit after another.

If you're serious about animation then start small. Don't make a piece with the intention of animating it. Make a piece and THEN add animation to it as a bonus. It all comes down to a mindset. Don't look at the piece as a whole as a mountain to climb, but rather each of the individual steps you need to get to the peak.

tldr: sketch out your frames first and make sure the timing and motion is good before you dive into the actualy pixeling.

one thing that helped my animation process was to start by drawing out the key frames first, rather than just drawing all the frames in order.  You can just roughly draw out all the key frames then duplicate them to figure out the timing. 

for example if the animation goes kf1 f2 f3 kf4, then start with frames 1 and 4.  Then if you duplicate frame 1 so that its there three times and play the animation you get a quick sense of how much time there is between frame 1 and 4, even if theres no motion (or maybe you then realize there only needs to be 1 frame inbetween, or 3)

Then you can start sketching out the inbetween frames, and keep making sure the timing looks right before you go in and do all the pixeling.  It sucks when you pixel a bunch of frames and at the end you realize all the extra frames make the motion feel too slow so you have to cut them out.

well I guess thats just more generic animation advice than pixel specific though.  And Im just an amature so better animators may disagree with my exact approach but I think starting with key frames is a pretty universally aknowlaged approach.

Well, not really; it was misundertanding that was very widely broadcast. "The serial numbers provided as a part of the download may only be used by customers who legitimately purchased CS2 or Acrobat 7 and need to maintain their current use of these products."
Consider it like any abandonware.

@r1k: Yes, that's a good method. Or, actually THE method to animate. I personally find the animation part harder than the pixeling part, but it depends on how complicated your animation and your pixel art style is.
As for programs, choose one with onion skin if you want to make an impressive animation. I know you can get a fake onion skin with photoshop too, but why making it so complicated when there are free programs which already have that? Also I remember the timing in photoshop animation is very weird, when I see photoshop animations they are almost all weirdly slow, which confirms that.