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Don't be dude, just do your best.
If I had to give any advice is, do the practice exams, study your portions, and then, just leave it at that. Don't worry about what they're going to ask.
It also does help to run over concepts in your mind :]
TL;DR - Don't worry. Drink a good (but not excessive :P) amount of water. Do the work, and you'll do FINE :]
How are you? :]