I found I didn't really understand the mechanics of the game (even months after playing) until I started watching streams of some of the pro players, aswell as watching some of the bigger tournaments.
http://www.solomid.net/streams.php has quite a few League streams up, and a lot of the top tier guys that play from teams like are streamers aswell. It definitely helped my game out a lot. Like mentioned before, mobafire is good and I use it as well. Also youtube has a crazy amount of guides on basically everything regarding League.