I'm really nervous about my Oral exam. How can I prepare?

The first thing to remember is that oral exams are nothing to be afraid of, just think about it as a chat with your teacher rather than as an exam. The more relaxed that you are, the more fluent you will sound and the better the exam will be. The next most important thing is that you need to get used to the sound of your own voice speaking French - this will make you feel more confident and less nervous. I suggest reading a piece of French text aloud while revising - it can be on any topic as long as you feel comfortable reading it, however I would recommend choosing a text which is relevant to the topics you are studying in class as this has the added benefit of introducing you to vocabulary. Now for the actual exam. The best thing you can do for this is be prepared. Avoid memorising a whole text as this can sound unnatural and can cause you to panic if you forget it. Instead try to remember some key phrases - especially ones that show a wide range of skills so that you can reach the top marks. A lot of the exam is ticking boxes so make sure you have phrases in the past, present and future and avoid sticking to one tense. Similarly, if you are aiming for higher grades have some other more complex phrases prepared too such as: a rhetorical question, an interesting use of pronouns or even a subjunctive phrase. Most importantly though, you should prepare some phrases which can fill time for you while you are thinking about how to answer the question. This will get you extra marks as it sounds more fluent to say 'what an interesting question' rather than pausing for a few minutes.