Give yourself plenty of time to prepare for a test or exam.
Develop a realistic study schedule broken down into the smallest applicable steps. Spread it over several days. Stick to both of these suggestions. It will help minimize your stress levels.
Set realistic goals during your study sessions.
Repetition of the material will build confidence. Overlearning is the best insurance from going blank during a test or exam.
Reach for excellence not perfection. Set limitations to your study sessions and stick to them.
Try studying no more than 50 minutes at a time. If possible break that time up by alternating subjects.
While studying try different things besides just reading the material. Active studying is thinking of possible exam questions and writing down answers without looking at your notes or text book.
Test yourself frequently but using old quizzes, tests, assignments or chapter questions.
Attempt rapid problem solving. Devise a set of questions to answer and put an appropriate amount of time to answer them. Practicing this replicates the structure of time limits you have during a test or exam.