This brings me back...I'll admit to nearly !!!!!ting myself when I went to do stalls for the first time, it is a little scary to say the least...
Anyway...get the old Trevor Thom book out and read up on it. Get a ground briefing beforehand, and know the procedure off by heart before you attempt it - checklist, recovery etc. No doubt your instructor will demonstrate one for you first, then give it a shot, once you've done a few of them you really will wonder what all the fuss was about!
Best of luck!