Something about using books to learn video software just doesn’t seem to work for me… Lots of video tutorials available instead.
Check out the different lynda.com series for After Effects - Essential Training, Beyond the Basics, Effects, Professional Titling Techniques (for AE7), etc. (lots of torrents available isohunt.com or PirateBay).
Creative Cow also has some great tutorials covering basic techniques up through more advanced stuff.
Pixel2Life offers lots of stuff too, but sometimes with mixed results.
Seems like there’s TONS to learn w/the program - so many effects, filters, parameters to play with. So far I’ve only been watching tutorials… I’m sure it has its frustrating moments, as with any animation work w/keyframes, timelines & keeping track of multiple different things, but also seems really powerful & combines great aspects of other Adobe programs. Likely lots of trial & error plus experimentation.