If you can get your hands on it/read it before you get to the show, the book "Everything Was Possible" by Ted Chapin will greatly enhance your viewing of the show in addition to listening to the wonderful new recording, as ljay said.
When I saw it this year for the first time in DC, I went in fairly blind (other than hearing the "famous" songs, largely completely out of context), and absolutely fell in love. The most important thing is that you see it, because it's a fantastic show that's getting a great production on Broadway with a top-notch cast. I hope your experience at the show is as unforgettable as mine and the many others on this board who have been equally entranced by it!
"Art, in itself, is an attempt to bring order out of chaos."-Stephen Sondheim