Practice practice practice. Do the entire thing, in order, with the appropriate breaks all in one session.
I practiced w/the AAMC practice tests that I timed and took at the library. Of course there are practice exams given in prep classes as well. The real test day was from 7:30-5:30 (we had to be there at 8am, but I had allowed for traffic and getting lost that didn't end up happening), and it really didn't seem that bad because my testing endurance was so good.
Reviewing concepts is important too, especially if there were things you didn't get the first time around. But be sure to understand the concepts, not just memorize stuff.