In the day
1. Don't revise too much! - There is definitely such a thing as too much revision. The day before an exams you should take it easy, you probably won't retain as much information the day before as you would a few days before
2. Have a good breakfast - This is important for both the day before and the day before exams. It's best to have a breakfast with slow releasing energy, like bananas or something with whole grains. Also recently I've been obsessed with drinking green tea. It tastes amazing and helps with your memory! Also make sure you drink lots of water throughout the day to stay hydrated.
3. Make flash cards - Make a few cards with the vital information you need for your exam and place the cards around your room either on the wall or on tables. It's also a good idea to place them around where you get ready in the morning so you can look at them while you do your hair for example. You can do this a week or two before the exam even but I personally find it so much easier to retain information from little flash cards than from huge pieces of paper with lots of writing
4. Take lots of little breaks - It's actually quite difficult for your brain to concentrate for long amounts of time so make sure you take a break, it can be anything from going to the toilet to going for a walk. That way you can set yourself little goals throughout the day and the rest can be your reward
5. Do some exercise - It doesn't have to be a lot of exercise but exercise is very good for your brain. As they say in Legally blonde: Exercise gives you endorphins, endorphins make you happy! It can also give you a good break from the stress of exams.
In the evening
1. Make a good dinner - Find time to make a good dinner, you need to eat healthily so your body and mind are happy. Cooking can also be your start to a relaxing evening and will get your mind off the next day. Try and eat some brain foods like oily fish, spinach, and other proteins to help your brain work through this stressful time.
2. Do something other than revise - Like I said before, you won't remember a lot that you learn for the first time the night before so do something to distract yourself. You can watch a film, have a bath, read a book... anything.
3. Get to bed early - You need to get a good nights sleep before your exam the next day. Nobody wants to go to an exam yawning with bags under their eyes. Also keep a glass of water by your bed to rehydrate when you wake up
I hope these tips help. My main piece of advice about exams is to RELAX, no matter what happens in the exam room, if you believe you can do it, you can!