Just dropping by to expand on what I said about slices. Basically you should read Riker's tut
on what way to slice and what way to not.
Okay so take this sig for example I animated the text. Save all of it as a gif.
55Kb and only little animation?
Of course most people then seek to lower the colours in the sig or re-size it lets see what we get at 128 colours.
45Kb not bad but look having a closer look at it the colours have already started killing the images.
This is where the slicing comes in. Grab the slice tool (K) and make a part around the animated part/s. It should look like this now
Then to select the format you wantfor each part.
Go to file-save for web and devices & select the parts you want to be. Eg top and bottom are set on PNG-8, 100 colours. The middle part is set of Gif 100 colours.
Image Ready Users
Go on the optimize panel and select the Slice Select Tool and click on the slices and optimize them in the panel till you satisied.
Then of course you have to make sure the slices are all AS safe and will connect properly without gaps. I usually just highlight them all and the details window will tell me the size.
Which is a total of 41Kb. Now remove the gaps between the slices and you should have something like this
And there you have it a nice & hopefully clear tut on using the slice tool