Jacket is definitely a good idea, although you Minnesotans are used to the cold. I've lived in SoCal my entire life, so 65 F is freezing
Take a mini pack of Kleenex just in case too.
Also, I would buy a timer if I were you, instead of using a watch, so you don't have to calculate how much time is life. There's a whole thread about timers on this board:http://www.lawschooldiscussion.org/prelaw/index.php/topic,4530.0.html
If you do decide to buy a timer, don't forget to cut the sound cords or otherwise silence the timer. I'm really paranoid, so I also took along my tiny little screw driver in case the cords moved around inside the timer and ended up touching again, which would make them beep. I also took along extra batteries just in case the brand new ones I had just put in died.
I had to park in a lot that charges for parking, although they opened the gates so you could just leave after the LSAT for free. In case yours doesn't do that, make sure you have a couple bucks with you for parking.