The only way to really prepare for english is to do more writing. I know. Shock.
Nah but seriously, the only way ur gonna improve for short answer response is by doing more questions and letting a teacher read ur response. We all have to start somewhere, and this is probably the best time to start.
Essay depends on how confident you are. If u think ur gonna struggle during the exam, be sure to go in with some memorised stuff. Of course theres your quotes, but also try to remember your main arguments/ideas and a little bit of analysis would do no harm too.
There isn't much you can do unless you are actually good at english, and in order to get to that point, you will just have to do more writing, and to think more in-depth rather than what's given to you. I.e. rather than similes, think about metaphors, symbolism etc
Oh, and be sure to answer the question, since you can't get full marks if your response doesn't link, even if it deserved full marks by itself.