How should I prepare my essays for the exam?

The first question to address here is; what genre is the material you have been learning in class fits. Is it drama, poem, prose, non-fiction? From here, we can look at past exam questions, and observe a trend in the sorts of essay questions that are posed, and collate these into categories.
Let us look at drama, for example. Questions asked have concerned tension-building, a key opening scene, a climactic scene, an end scene, character and theme. For each of these areas, it is a good idea to identify key points, quotes and analysis that could answer that particular question. Don’t worry about trying to fit everything you have learned in class to every question, just the most relevant bits. You’ll find that quotes and analysis you find may cross-over, so once you start finding content for, for example, a climactic scene question, you may well be finding points for a tension-building essay too!
You will end up with a separate collection of points, quotes and analysis for each category of question the exam might ask, like looking at the one piece from many different angles! With these you can begin to form some essay structures in response to questions. With the content you have found, can you build an argument? Does the question ask for, for example, a certain opinion on the effect of the ending scene in this play? Try and use your material to create some discussion. In the heat of the exam, it isn’t unlikely that you may pull ideas and analysis from your other essays to strengthen your discussion.