What's the best way to prepare for the listening exam?

Consistency is key! The best thing to do is to start early on in the year and keep at it. You don't even need to dedicate huge amounts of time to listening practices as you can download some podcasts or songs in French to listen to when you're on the bus or in the shower or revising for another subject. You can even watch French YouTube channels or watch Netflix original series with French audio (some of the other selections may have the French audio option).The main difficulty with the listening exam is not being comfortable with the words. The vocabulary will be learnt for the other elements of the French exam but it is no use knowing what a word means unless you are used to hearing it being said. So, again, listen a little every day in preparation for the listening exam.