I'm graduating from the International Baccalaureate Diploma (IB) Programme in my high school, and I've learned a few valuable lessons for studying that will probably translate to all higher level (AP, IB, college level etc) classes:
1. Keep two notebooks for each course. One for class, and one for home/library. Take notes regularly in class (like normal people). Then, either every time you have the class, or before an exam, copy all the notes from that unit neatly and as organized as possible into your second notebook. Re-writing helps you study, and then at the end of the year, or for any other cumulative exam, you have a succinct, neat and organized study guide. Do not type it! Writing in your own handwriting makes you remember it a lot easier than word processed font. I don't know why this works for and a bunch of other people I've talked to, but it does.
2. Go to your professors' office hours/extra help/tutoring sessions (whatever your school calls it). In our school, every morning, starting an hour before classes begin each teacher is required to be in a specified classroom to meet with students. It helps... A lot. Don't just go when you don't understand something, or right before a test. Showing your face more often shows that you care, and you're interested (even if you're not). I can't guarantee it'll get you higher marks, but I can guarantee it won't. The top three kids in my school (going to Yale, Princeton and Harvard, respectively) all go to these hours routinely... Like at least three times per week. It sucks sometimes, but it's well worth it.
3. Don't cram. I hate to say it, because I usually resort to it, but it never works. If you have the time, like I said in my first tip, re-write down your notes from the class every day you have the class. Instead of studying a whole unit before an exam for a few hours and getting burnt out, you probably will only need to study less than an hour if you re-write and review for just five to ten minutes everyday.
4. For math and physics classes where there isn't wrought memorization, don't view a problem as a "note" like in history, biology or chemistry... View an equation or formula as a sequence. Memorize the steps and patterns, not individual numbers hoping that something similar comes up on the exam.
5. Consult others/books/internet/YouTube. This one a lot of people are skeptical about, but for me, it has worked wonders. I have a calculus teacher who literally has no idea how to teach. She is nice, smart and thorough, but for some reason my class and I cannot "click" into her teaching style. I found a great tutor on YouTube.com who makes videos for everything in calculus... From things as simple as the power rule to as difficult as differential equations. The same should go for physics, chemistry and so on.
Hope I helped... These are vague and seemingly simple, but are very effective if employed properly. Happy learning, and good luck with high school. Make it count!