Read the question. Try to figure out what the point of it is. Stick to the point in your answer. And I do not give partial credit for correct but irrelevant information. Having said all that, you should of course make full use of relevant cases, citing them by name.
Cases are important.
But so are other things. The number two most common error on law school exams consists of misunderstanding the nature of legal writing. Good legal writing is clear, precise, and well-organized. It is written in plain, simple English, with as few long words as possible. There is no point in trying to be clever or funny.