First don't think that you will fail, if you keep thinking you will fail you will.
Try staying calm as much as possible, if you made a minor mistake and you know it, just forget about it. You get around 14 mistakes I think ( I don't remember)think one mistake oh well, just be more careful. Don't make a mistake and panic, or give up.
Remember the automatic fails, I don't know them all, but I learned them through my friends, and driving instructor.
-automatic fail if you drive pass a stop sign, drive on a crosswalk, hit the bumper while trying to park your car.
more tips
-Make sure the instructor sees you looking right, and left and all your mirrors. Make it super obvious,exaggerate more than normal. You might get mark down if you jest use your eyes to look left and right, cause the examiner might not see it.
-Forget the other stuff, think of driving only.
I said it already but BE CALM.