I'm not sure about World History, but AP American History is a NIGHTMARE. We have to rewrite the Declaration of Independence. Really! In my case, homework isn't due everyday, but we sure get a load of it. Projects are one after another and more responsibility is put into self-study. You really can't just breeze by. But it all depends on your teacher and their methods.
Just study a bunch of important events in history, including military, economy, culture, even a bit of literature. And I didn't have much homework when I took it besides note-taking.