Really good advice from Herbo! Just to tack on a bit -
I started running Pathfinder specifically to run Rise of the Runelords. I have run other games for years, but this was my first time for Pathfinder. I said right up front that we were not looking up rules much - I would make a ruling and we would look up rules later and e-mail the correct ruling out to everyone so hopefully one of us would remember the next time it came up. It's worked wonderfully for us.
There's a lot of rules - don't let 'em drag your game down ;)