Hey, I'm taking AP Biology as a sophomore next year and I really want to prepare myself since I hear it's one of the most challenging AP class in our school. What books or tools most helped you when you took AP Biology? (Cliffs, flash cards, etc.)

I'm also thinking about purchasing the Oxford Dictionary for Biology so that I can look up key terms. But then again, I don't want to waste $15 on something that might not help me as much as I want it to. Will a biology dictionary be helpful, especially since I haven't taken Biology in freshman year? Many thanks!