Updated: Jun 3, 2020
Very briefly, here are a few answers to questions I've often received:
How many AP's should I take?
This will be different for every student. It's a delicate balance between taking enough AP exams throughout high school without taking more than you can handle. Your goal is to get all 4's and 5's on the exams. For some students, this means taking two AP exams junior year and then four senior year. For others, it may be taking two AP sophomore year, four junior year, and four senior year. The same theme of quality > quantity applies. Scoring a 5 on four AP exams is far better than scoring a 3 on six.
How many subject tests should I take?
Depends. You should definitely take the Math Level II Subject Test after you finish Pre-calculus and before you begin AP Calculus. Why before Calculus? Calculus is very different from any math you will have done before and is not included in the subject test. The subject test also covers concepts up to Pre-calculus.
You should also pair AP exams with their respective subject tests. For instance, if you are taking AP U.S. History, plan to take the U.S. History SAT Subject Test. This is how you can get the most test score-wise from your hard work.
And based on personal experience, I would recommend taking at most 2 subject tests per testing date unless you're a genius and have the endurance of a marathon runner. So if you are taking 4 AP exams one year, just choose the top 2 (or 3) to pair with a subject test.
How do I get my grades back up?
The answer varies from student to student. You should find why your grades are falling. Is it because you find it difficult to focus and get distracted easily? Then put your phone in another room, study only with books, and download website blockers for distracting sites like Motion. Have you spent a lot of time studying but see no improvement? Adjust your learning method. Maybe flash cards is better for memorization than reading text over and over again.
Bottom line: think critically about the root cause and test different strategies to combat that.