Study by doing. That means working problems. Go back and forth between the problems in the Study Guide, the examples in the lecture, and the material in the textbook. If possible, study with others. Explain the material to them.
Most teachers are no more intelligent than their students.
They know the material because they've had to explain it to someone else. When taking the test, read the question carefully before you begin writing a response. You'd be surprised how many correct answers are given to a question that wasn't asked. Some students do well on tests even though they are exhausted. Try to get rest before a test.