How to Improve My Writing - Writing Submissions for Interviews - Cover Letters/Additional Writing on Interest in Real Estate

Hey guys,

Serious question, what is the best way to improve on writing for a job opening that asks for a sample/please write about xyz to be submitted. I am not the best at this and want to improve. Please don't comment "If you can't figure out how to put together a few paragraphs you shouldn't be applying" or "no one looks at it", I can put something together but I have never been known as a good writer. I understand it may not be an integral part of the submission and they very well may not look at it, but if they are asking for additional documents it seems they will review it at some point/use it to weed out one candidate at a point if it's close.

Any advice to improve in a short timeframe (a week or so) for roles I am looking at? I plan on writing what they ask then reviewing it at least once a day later with fresh eyes before submission.