| You should study exams that actually matter. Human Geo and Psych are pretty meaningless. If I had known how easy self studying was, I would have done Econ and a science last year. (I did Comp Gov and Psych, both 5's). I do recommend Comp Gov though, I really liked self studying that.
But if you do stay with the 4 you listed, you only need prep books. For Comp Gov I started 2 weeks before the exam and read my prep book three times through. For Psych I started 3 days before the exam and read my book two times through.
I'd recommend you start sooner so you can actually have a life the weeks before the AP exams. |