What should I do to get ready for an open call for a modeling agency?

In my newspaper, there's an ad looking for models of "all shapes & sizes, all ages" to be used in advertising, film extras, runyway, etc. It says inexperienced is welcome. (I am a 22 yr old but do have a wee bit experience--when I was a baby, I modeled for a very successful card company.) I am considering checking this place out. How should I prepare for something like this?? (if the agency did hire me). I am a 5'3" attractive female. I don't have a huge ego, but I am confidant and am aware I have a rockin' body & cute face. What should I wear? What would I expect? Any people with experience/tips in the modeling world is appreciated! I do realize modeling can be tough work. Thanks.