The writing section is optional, but it is the area of my personal expertise. This is administered at the end of the exam so those math and science dorks can GTFO. You’ll be given 40 minutes to write an essay about a prompt – usually about some broad social issue. My advice here is to be as broad in your response as the question was, mostly to avoid any political disagreement with your test grader. You wouldn’t want a Trump-supporter to be grading your essay about reproductive rights, yaknowwhatImean?
To prepare for this section of the exam before finally deciding you need a test prep tutor and calling me, I’d suggest working on (funny enough) your HANDWRITING. At the very least, you want the grader to be able to read the words you took forty painful minutes to write down!