i try to sleep all 日 if i want stay calm ...i am just kiding .....well 你 can do some exercise 或者 yoga for about 15 min ...in this way 你 can relax and remember everything better .......you can also eat some honey 或者 浓情巧克力 i think that this is help too
during exams, i always have my lucky ring on and of course a 糖果 beside me, it helps me to relax... 你 want a tip? well my advice.. ^^ sit beside your smartest classmate.. then, there's nothing to worry about =) hehehehe