I've heard from a number of models AND photographers, and tend to agree, that the true genius of a great model is "being able to do the most painful, uncomfortable, ridiculous things and make them look completely natural while looking good."

I think that's where a lot of your posed/unposed dichotomy comes in, for MANY things (especially a lot of commercial work, art nudes, SOME fashion altho high fashion & especially haute couture tend to be more stylized) "unposed" looks more "real" or "natural" and so sells the image better.  It's REALLY hard for a lot of models to "just look natural," especially when being posed.  That's certainly why many photographers, especially outside the agency realm, prefer experienced models.

Take either of these shots, both done in the last couple of weeks:
     
Both are posed/staged, altho I didn't micromanage.  I gave the models an idea of what I wanted & let them set their own looks.  Of course Elizabeth & Artemis are both VERY experienced models.

The risk you run when trying to "force" a look or pose is that it DOES look staged, and aside from a fairly narrow set of looks that rarely works.  I think it's an advantage for you, Rosalind, that you've had dance training.  Dance experience (along with some other things like yoga) can be a huge advantage for a beginning model in being able to do something very artificial & unnatural (posing) and still make it look "real" for photos.