Preparing for a role is my favorite part of a play. Except actually performing. That's saying a lot, too, because I even like tech rehearsals. (The only thing I don't like about performing is the initial meet and greet, where the very excited production team meets the actors and tells us what makes this experience unique. After signing a contract, getting measured, meeting the cast and getting my script, I can save the socializing and stories of past productions until the production is up and rolling.)
Yesterday I checked out a book on Oklahoma Territory. I've read Green Grow the Lilacs to find some more interesting character traits (there are tons), and I've also checked into what books were published within 15 years of 1906 to find out what her influences may have been. Or which ones I'm choosing them to be. I've looked up movies set in Oklahoma besides Oklahoma! to get a real accent started as I learn lines, and I've started developing a back history and motivation for Laurie based on interchanges in the original play that didn't make it into the musical. I know who Curly is, how much older he is than she, how long she's loved him, and how long he's known she existed. I know where she grew up, what happened to her parents, and why she escapes into dreams and is so frightened of something bad happening.
The audience won't be aware of any of this, of course, but it helps me to know all of this about her, making her more than a two dimensional musical theater ingenue.
My script has several pages of post it notes in it, and I spent the other evening with a pot of tea and a yellow highlighter going through my script. I love my job!