Good luck! I feel the GMAT tests your mental and physical condition more than anything.... pretty much anyone who knows the material can do well on the test, but to me it's a matter of concentrating and being on your A-game for the 4 hour duration. Bring lots of food and drinks! I had a Gatorade, a bottle of water, an apple, 2 bananas, an orange, an energy bar, AND a chocolate bar in my 2 breaks!

(OK it's overkill but I still felt energetic when I left the test centre so I believe the food served their purpose)
For verbal, I'd recommend spending a little bit more time on the first question on RCs... I found that actually knowing the content (as opposed to skimming) really boosted my RC score....