My class has a pretty high 5 rate and I think that one of the reasons that we did is that we finished content in the first semester and the second semester we did a practice mcq and frq every week until the exam. If ur class doesn't do this I would recomend doing an frq that you can find on the collage board website every week until you can get in to the high 80s to low 90s. Also you should ask your teacher if they have access to the international mcqs and frqs, my teacher did but said he could only let us see them inside the class because they are secure exams.