The first thing is to do well in the class. Then, if you want more preparation buy a review book. I did not buy a Calc BC review book and got a 5. This is because my teacher did an outstanding job of preparing us. We did practically every past AP exam released. However, for the US exam, I used AMSCO, which was a good summary of what we did in class. I did buy a review book for English language, but I did not use it very much. If you read carefully and can write well, English language will not be a problem.
I am in AP Chem right now, and I will probably buy a review book just to see what is specifically emphasized on the test.
If you can get old AP tests from your teachers, I would highly recommend looking them over, they are the best way to prepare for the test.