1. Answer the Question.
This is the first and most important suggestion. Answering the wrong question is a common mistake made by students. Unfortunately, it can be a real disaster for the grade you get in an exam. Make sure you understand what the examiner wants; it is highly advisable to refer back to the question throughout the answer. This point may sound like stating the obvious; but, in my experience, answering the wrong question is the biggest cause of a disappointing exam result.