Preparing a Monologue

I have acting experience, but it's all in an operatic setting. I know how to go about learning and preparing for those sort of auditions and roles, but now I am moving on to something a little different. I'm auditioning for our local shadow cast of The Rocky Horror Picture Show. It's amateur musical theater at it's finest, but I am have to go in with a prepared monologue and I have never done this before. I figured there have got to be a couple of actors around here who might have tips on the process. I shouldn't have a problem memorizing it, but there's got to be more to it than that. Right? Any Insight? I'd appreciate any tips.

 

Well, I am auditioning for Columbia and assuming they want parts from the movie I was planning on her breakdown just before the Floor Show.

Then I figured I'd sing and do the choreography for the Floor Show.

I am not sure if that covers what type of monologue...