Imagine you were grading the exam. You were checking fifty scripts with the same answers in a short time. What would you like in the answer sheet? You would want to ensure that an answer was accurate, had all the required information and qualities, in the shortest possible time, wouldn't you?

So give your examiner what s/he wants. Make your handwriting clear and legible. Highlight all the key points. Pay special attention to the introductions and conclusions, because those are the parts that will leave a lasting impression. Include diagrams, quotes etc. to make your answer exceptional. (Ensure everything you are adding is relevant to the question though.) Start with a question you know well, and end with a question you know well. This will leave a good first and last impression with the examiner.