Is it similar to the edexcel iGCSE course? We have one question on the anthology text, one of an unseen and one for creative writing. If you are doing any of those, here are my tips:
Anthology: You're given the text, so don't try learning all of the techniques at home. Spend the time practicing your writing speed so you can write loads. Also try to learn how to make stuff up around it. Like: "the writer uses the (insert technique) to create a sense of (insert whatever fits)...". From there just add in good vocab. Also remember to plan it if you can. Just underline the bits in the text which are useful or make one up on the back. scribble it out though if you do.
Unseen: Can't really help you. However, here's what I've got. Just find techniques, even if you're scraping the bottom of the barrel. No matter what, the exam isn't made to force you to fail. There will ALWAYS be at least a few techniques. If in doubt, use 'list of three', 'short clause' and 'imagery'. List of three is always emphasis of something. Short clause is generally tension. Imagery is free.
Creative: DON'T WRITE ABOUT SOMETHING REAL. Life is boring. Therefore, make something up. Something that's not completely unbelievable (e.g. aliens or demons) but something interesting for the examiner to mark. So I would suggest doing something concerning death. Death is great to write about. You can write about olfactory imagery (smell), such as rotting flesh or something. You can do the whole, 'blood pumps through my body' thing. And a lot of scenarios have it that are interesting. But don't focus to much on the plot. Remember, they're judging you on use of techniques. So remember to use similes, metaphors and rhetorics.
I know this probably isn't the best, but it's something. Good luck!