One of my main problems was structuring essays (for English language especially), so make sure you're confident in that. Do a lot of past papers, and find the predicted questions online or from your teacher so you know how to answer the harder stuff. Revising with your friends is good, because it's more fun and engaging than being by yourself.
Make mind maps or cue cards for the main themes and characters in all the books/ poems. Write down main quotes that match the themes and characters, then write short explanations for both the language and structure of them. For most quotes you'll be able to bend them so they fit the question, this will be super useful for if you get stuck!