During finals my two pieces of advice are trying to allot time to get outside in the sun when it’s nice out, so I don’t feel like a cave bat the whole time. And second, surrounding myself with snacks.
Don’t put things off till the last minute and make sure to get sleep and eat food. While it’s technically possible to pull all-nighters and exist only on caffeine and energy drinks for a day or two, it’s definitely not the best method of acing final’s week and can be absolute hell on your body.
My advice would be when time managing, allow even more time to do something than you think necessary. Often times, I find myself underestimating the time I need, and then being behind schedule stresses me out more. Overestimating segments of time is best, and lots of coffee!
Don't forget to take breaks. I find I'm not as productive studying or writing for several hours straight. So I always try and have some music ready or a good T.V. show, just to step away from my work and clear my head.