My method, regardless of the scene partner, is to figure out what my character wants and, perhaps even more importantly, what kind of reaction they want from the character they're speaking to.
So as Sally, does she want to impress Cliff with her worldliness? Does she want him to feel empowered to write his novel? Does she want him to fall in love with her? The more specific you can be, the more you can embody the character, and your nervous scene partner may naturally gravitate to what you're doing without even realizing it.
But specifically to this character. Sally projects this vivacious, sexy, sophisticated ingenue. But really, who is she? What do her actions and her surroundings say about her true nature? Bottom line, there is a ton of things happening around her, especially politically, and she will do whatever it takes to not let it affect her.
Just my two cents.