The night before the exam, I rented a DVD and chilled out. Since I set the test date, I knew I would be ready by the time that date came. Of course, I had my last minute doubts, and I think that's only human.
The only thing that I did the dy before the exam was go over Kaplan flash cards and a couple of subject tests...nothing to intense though.
The morning of the test, I went for a blood rushing run when I woke up to get the blood flowing. I had a quick breakfast of Honeynut Cheerios, a glass of Carnation Instant Breakfast, and a glass of orange juice along with all of my vitamins.
At the test center, I popped a Hydroxycut (don't recommend it if you're not accustomed to it) before I went in to take the test. At the break, I had a BabyRuth and another Hydroxycut (Ephedra Free, of course) prior to the RC and QR section. I was so surprised how relaxed I was once I got to the testing center.
So my recommendation is to do your best to relax if you've been doing decent on practice tests. Watch a movie, have a nice dinner, walk the dog, etc. Oh...and have as many people that you know say a prayer for you...that worked for me too.
Good luck, and let us know how you do.