First of all, understand the text to the best of your ability and pick out the themes, ideas, quotes and techniques that supports your interpretation of the text (i.e. the general direction of your writing).
Then do a
ton of timed practice essays - so much that your hand will ache and you'll begin to question the fabric of your existence. Can't find practice questions? Make some up.
It's brutal, but it got the job done for me: I went from being ranked roughly 56/85 (out of the students who picked English Advanced) at the end of Year 10 to 8/85 during the final semester of the HSC year (and graduated with Band 6 in the subject).
Just reading the process will probably make you dread it, but just think about this for a second: your first attempt at a practice question is your first draft. Each time you attempt a
different practice question, your draft gets improved, e.g. coming up with better sentencing and presentation of your ideas, using better evidence, et cetera. By the time you hit your 6th practice essay, you've not only fully memorised your ideas, techniques, quotes, and your entire essay even, but you've successfully produced an essay that is insanely polished, and you will also be comfortable with improvising and adapting your essay to different questions (since you've been practicing them on slightly different questions each time). You'll also improve on writing quickly and consistently, which is essential for your exams.
The thing is, it doesn't actually take up that much time! Spending time researching your text and ideas will take maybe an afternoon, but once you've done well enough, you don't need to do it again. And each time you do a practice essay, it should take roughly 40 minutes (it's okay to go a little over at first, but you want to aim for 35-40). So if you do one practice essay a day, you're only using 40 minutes of that day, which is nothing. And after a week, you've hit 7 practice essays, and by then you're probably on your way to doing beautifully in the exam.
I've hit upwards of 12 practice essays for the internal assessments for the modules/AOS, but I think doing at least 6 is enough. Obviously more is better, but it depends on time constraints and whatnot.
Finally, if you're unsure, it's worth sending your essay over to your teacher for their feedback. That said, it's also okay to disregard some of their feedback, if you feel like it's too big of a risk.
Here's a link to my English Advanced essays, if you need an idea of how to structure your essay and how to tackle the questions.
Best of luck!