Don't think that you had forgot everything.
Don't try to prepare new chapter before revising the already prepared chapters.
Don't awake whole night.
Don't eat heavy.
Don't read anything just before the exam.
Don't repent that you couldn't study well
Don't start writing before reading the paper twice.
Don't use to many pens for writing.
Don't put wrong question number.
Don't put your pens and other things anywhere otherwise how will you get them before the exam.