Without water, you will die. :o
That said, it's not at all required to drink pure water itself. Besides, you get the majority of your water from the food you eat.
Anyway, just get plenty of rest, drink enough liquids and have some that's easy for you to keep down.
No carbonated drinks, that means no Coca-Cola or Pepsi.
Keep away from all the crappy junkfood you're probably used to snacking on.
Also, it's probably best not to spend lots of time on the computer or watching TV or playing videogames or even reading. Repeatedly doing so can give you headaches, so make sure if you do, you take breaks. You don't want to feel like even more crap.
