Hahaha, I had the same experience for my half-yearly exams. Did so bad in the Writing Task because I didn't prepare anything. I went for the Writing Task session during Sydney West Lectures and I was inspired so much! I got 14/15 in my Trials after that. Aiming for 15 this time! =P
We were told to prepare at least 2-3 'plots'. They shouldn't be cliched (e.g. don't do something about your tragic Year 12 life, don't do soap opera-style love stories, no extensive shooting/fighting, no complex, drawn out Sci-Fi's, etc).
That doesn't mean to say that you're not allowed to use parts of your own life or others' lives to write a story. Use your interests or elements from other things you've read or seen to find a theme for your story. Just don't copy them completely!
Also, don't be afraid to be surreal - that's an imaginative journey you've got there. Don't make it sound too warped, I think. Always have a thesaurus handy when you're preparing your responses!
Remember that you don't necessarily have to use humans as your protagonists. Animals are fine to use. To make it that more epic, you can have an ending where it suddenly reveals to the audience that the characters are non-human!
In terms of descriptive language, only use it when it's appropriate to the story. So don't talk extensively about the interior of a house when the next paragraph of your story is going to be something happening outside of the house. (LOL bad example, but I hope you understand ;P)
Not sure what else to say...=S
Hope this helps you somehow!
(BTW I think this post shouldn't be here? Ugh, don't really hang around here much =S)
