while jumping in head first is my favorite policy, there's still plenty of places that have insightful tutorials:
video copilot has tons of excellent content to help you out. andrew kramer is probably the best guy to listen to cause he gets right to the point and actually walks you through what he's doing, rather than the other lame-o internet tuts where they joke around or tell you a life story half way through
tuts+ has a lot of helpful after effects stuff too. some of it is effect based, while some is post production fine detail stuff
there's a couple of good youtube channels ill link you to:
mt. mograph is a wonderful channel. he does a lot of great flashy text/cartoon based motion design. he also does some work with c4d and blender(?) if thats your thing too
ross plaskow is pretty great if you want to learn how to do cartoons. i personally cant stand his voice (lol) but hes got some great tips for doing cartoon based animation
ECAbrams has some interesting text based videos. hes very joke based but it doesnt get in the way of the tutorial too much, so i figured id list him cause ive also snagged some tips from him
video copilot's youtube channel has just about everything on the website, (cool explosions, 3d element stuff, logos, compositing techniques etc) but ill include it too just in case
as for plugins, video copilot, red giant, and trapcode have some of the best stuff you can get. if you can get them, id definitely recommend it