When I'm playing something for the first time, I try to play it at a slow enough tempo to play everything correctly, including dynamics and accents. Then, I take it by sections and increase the speed as I go. Just remember, you don't have to get everything up to lightning speed on the first day. That's why daily practice will get you further than trying to cram it all in for a couple of days. Also, Gregg Bissonette told me that if you play something 21-22 times, muscle memory will kick in and you'll start to retain it. Good advice!
Mike