In order to achieve a high mark, it is important for you to include all the assessment objectives in a well-distributed fashion. While writing your essay a good tip is to quickly note down the AOs in the corner of the paper and tick them off whenever you include one. By the time you finish the essay, you will be able to see how many AOs you have addressed. Furthermore, it is important to present your ideas in a formal way, try to include as much terminology as possible and make sure you're writing is easy to understand to the reader. This can be difficult when given the time pressure, so before you begin make sure you have a good idea of what your time limits are and how you can equally distribute them among the questions in the exam paper.