So here is how I make gifs. You can see a lot of them on my tumblr (because that's where gifs go right? xD) I'm going to be making a gif of Sailor Mars from PGSM.

STEP ONE:
The first thing you're going to do is make sure your Photoshop is in 32-bit mode or this method will not work. I'm using Photoshop CS5 for reference (I know this will work in CS4, but I'm not positive about lower versions). You can do this by opening your Applications folder > Photoshop > Get Info.



STEP TWO:

Once you've opened Photoshop, go to File > Import > Video Frames to Layers



STEP THREE:

Select your video file. It usually requires avi videos. Sometimes you can get away with mp4, but mine won't let me so there's a really good converter called Handbrake that you can convert your video to mp4 and then just change the extension to avi once it's done converting.



STEP FOUR:

Make sure Selected Range Only, Limit to Every __ Frames, and Make Frame Animation is checked. It's recommended to use 2-5 frames (though I personally never go over 3 or it gets choppy). Once you've gotten to the part of the video you want to gif, pause it, hold the shift key, and press play. Continue to hold the shift key while it plays and a little dark mark will come up indicating your frames selected. Once you're done, hit OK.



You will now have a frame by frame animation. You can change the speed by Select All Frames and clicking the down arrow where it says 0.# sec. I usually have my gifs at 0.1 or 0.15, depending on how it flows.



STEP FIVE:

Since the video quality isn't the best, I cropped my gif to 300x200. You can crop it however you want (but note if you're posting to tumblr the maximum width is 500px).



STEP SIX:

This is an optional step, but I always enhance my gifs. I'm using a psd I made myself (there are LOADS of coloring psds on the internet). Make sure it's on top of all the rest of the layers.



STEP SEVEN:

We need to sharpen it now. Select all your layers in your layers palette and switch to timeline. The timeline button is right next to the arrows on the frame animation.





Once you've got your layers selected and are in timeline go to Filter > Convert for Smart Filters



Your layers will look like this



Then you're free to sharpen (Filters > Sharpen)



STEP EIGHT:

Time to save! File > Save for Web & Devices



Save as a gif. Be sure to set your looping options to forever. Otherwise it'll only animate once.



Click Save, name it whatever you want, hit save again and you're done!

FINAL RESULT:

My next tutorial will be making multiple scenes in one gif as seen here (there are two gifs per nine slots)

Hope this was helpful!