Look over the test and make sure that you understand your mistakes. If you don't know the answer to a question, look it up, ask a classmate or ask the teacher.
If the teacher reviews the test in class, be sure to take notes on what the teacher wanted for an answer on the questions/problems that you got wrong.
If you aren't satisfied with your grade, go to your instructor and see if there's a make-up exam or any extra credit you can do.
Save the test as study material for future cumulative tests.