Spanish Speaking

I would say practice a few key phrases. Maybe something like 5 good structures, and then 5 high level vocab phrases (that relate to the theme ofc).
Then if you get stuck on a question you can mentally go through that checklist of ten things and pick one that fits.

If you can find someone to talk to in spanish, or go through your flashcards, right before the exam so your brain is already in spanish mode. Also make sure you have something for the unprepared question before you go in! And an answer in case they ask the question back.

Mostly just remember that it's just a conversation, don't worry if you don't understand something just answer as best as you can or move it on. If this happens try to use "puedes reformular/repetir la pregunta" and "todavía no comprendo" or some variation that you will remember.

Good luck! And don't get too hung up, however it ends up it's only 15 minutes of your life after all

P.S. I've always found that taking a shot before an speaking exam helps with the confidence aspect. For legal reasons I absolutely do not recommend this. But it does work...