Having just had my french oral which went okay (fingers crossed) the trick is to be prepared and feel and act confident. I would advise learning off by heart really well, 4 - 5 prize sentences which include good tenses, vocab etc and can be used in many circumstances eg "im very much looking forward to it" or "i would like to return there" and even random things like, "i went ice skating at the local ice rink which was fun but i fell over a lot. " Then in the oral try and include all the sentences you remembered and you are guranteed good marks and will come out of the exam feeling happy! Good luck!

If possible, get a mock oral with your teacher. This should pressurise you into learning some answers!! When there, you'll find you can speak far more french/spanish etc. that you gave yourself credit for. Your teacher can then encourage you and advise you which topics you need to "brush up on".

I have the same problem with stressing about oral school exams, best thing to do is literally to tell someone your fears and how your stressed once its out in the open you'll clearer and more confident.