Pace yourself: Try to stick to a calendar to get through most of the concepts (or don’t). This way you’re most likely not cramming everything the night before.
Read: You don’t have to read word from word out of your entire textbook at the last minute. Read whatever feels the most comfortable and understandable to you.
Note: Remember that not all courses/schools/colleges use the same textbook, so make sure to focus on the concepts the most. Examples out of the book help with free response.
Study Guides Help: Whether online or as a book (I found Princeton and Crash Course books the most helpful).
Quizlet has flash cards for nearly every AP textbook in existence.
This site has hundreds of AP practice tests and hours of videos.
Google Scholars helps with finding specific texts from published works (to look for certain concepts).
Crash Course: World History, US History, Chemistry, Ecology, Biology, Literature, Psychology, and more.
BBC Languages (free online language lessons)
This masterpost with all sorts of learning stuff that helps a lot
Another masterpost with these learning websites and more
Listen to Music: Classical music is great for the mind. Video game music is designed to help you focus. Not your type? Film soundtracks work as a great alternative too.
Take a Break: Go at it in a pattern. 5 minutes the first two breaks, 15 minutes every third break. Every 30 minutes, get up and stretch. Here are some stretching tips for sitting too long.
Everyone Studies Differently: And at a different pace. Some people have the material down packed and only have to glance every once in a while. Some people study like crazy. Some people don’t at all. FOCUS ON YOU. Ignore the naysayers. Study all day if you need to.
Take Naps: Power naps are the best. Especially 30 minute ones. So your brain isn’t so wired while really trying to fall asleep, stop studying at least 30 minutes before you go to bed.
BREATH: Breathing exercises help for panic attacks. Take slow deep breaths every once in a while.