plan it out. I know u doing year 10 entry, so u have plenty of time to make a plan. Plot twists can be good but it might be overdone. Jus try to make a storyline that keeps the reader intrigued, allure them to different assumptions and let them create questions of your characters or setting, for example your intro could start out with "I was sweating profusely in my tangerine uniform, all I could think of was a blissful cold breeze of fresh air outside this dug tunnel." I know its only one sentence but it gives a lot of information. "Maybe the protagonist is a prisoner? Are they trying to escape? Why are they in this position? let me find out more" this is the type of reaction sought after in creative writing. Also from this lone sentence I can build a lot more of the story, like one pathway is talking about the past, maybe if the prompt asks to include some pictures, so I add that in the backstory. Another pathway could be them getting caught, and the quote the prompt asks you too add(if they do ask) can be implemented their.
This is jus my way of thinking, sorry if I yapped.