1. Read things (the textbook, for instance) multiple times. Each time focus on things that you didn't get. They will look different to you each time. Test yourself by asking yourself questions while you read. Cover up example problems and try to work them yourself, only uncovering a portion after you have attempted the next step.
2. When you read for details, look up things you don't understand.
3. When you read to get the big ideas, skip past things you don't understand, unless they seem like big ideas.
4. Take notes on your reading. The Cornell Notes strategy to the right is a helpful way to take notes.
5. Get some scrap paper and write things down (equations, for instance) over and over again, if you are trying to memorize them.
6. Make flashcards (word or equation on one side, meaning on the other), and ask someone to "flash" them at you.
7. Try to use a vocabulary word in the correct context.
8. Get a study buddy from the same class and ask each other questions about the material.
9. Ask the teacher, either in person or via email. Make sure to make a good effort to answer the questions yourself, first.
10. Save all of your old papers, keeping them in chronological order, and review them frequently.
11. Get out old tests, quizzes, or other assignments. Cover up your earlier answers with a piece of scrap paper, and attempt to answer the questions again. Check your review answers by uncovering your earlier work.
12. Use another resource (the web, or a book, a friend, a parent) to read or learn about things in a different way. For example, HyperPhysics or The Physics Classroom may give you a different perspective than the textbook or class.