Memorise the books a month before the exams and attempt a few past papers just to ingrain the knowledge (and to get a confidence boost), then start finishing off every paper I can get my hands on as I approach the exams. It's a strategy I've adopted for A-Levels and it's working out well so far!
Make sure you're prepared. Rather than learning and understanding the subject you should instead learn how to answer the exam paper. There will be "model" ways to answer each question which your teacher will likely go over with you; answering in this manner saves time since you're not writing down crap that isn't getting you marks, and also won't miss any marks either.
Sleep the night before an exam is overrated. It's far better to stay up cramming and rote learning if you have to than make sure you get a perfect sleep - chances are you won't anyway, so why bother?
Get up early for the exam so that you can go over everything you've memorised again just to make sure that you've not forgotten it.
Remember, exams are a memory test and nothing more. The sooner you release this despite however much you may feel that it's wrong, the sooner your grades will increase whilst your effort spent obtaining them decreases.