besides that, food and drink is essential. its a long and tiring day, and in my opinion, its not a day for watching your diet. i would always bring with me several sandwiches, a bunch of snacks, and something to drink. green apples in particular would help me feel a bit refreshed.
with only a few days left before the test, i would also completely stop studying and just rest. cramming the last few days and going into the test tired or burned out would do more harm than good.