There are a lot of simple techniques that you can use which will make you stand out from the other students taking the same exam. For example, it is extremely important to make sure that you demonstrate your understanding of all the different tenses in Italian by making full use of them in your written and spoken Italian. A student who is able to switch confidently and accurately between tenses is very impressive to the examiner. Even if you don't feel entirely confident with the grammatical structures, there are plenty of set phrases that you could learn. Furthermore, if you are capable of varying your vocabulary when you speak and when you write your essays it will help you massively when it comes to hitting that A* grade. There are so many different ways to say 'therefore' in Italian for example (perciò, quindi, dunque, pertanto etc.), and by using all of these (instead of just repeating one of them throughout the exam) you will be able to demonstrate your sophisticated knowledge of the Italian language.