I've already had a chance to work with a few people on their first time modeling and it's a mutual learning experience. One should avoid the nuisance that there are "good" and "bad" models, just appropriate or inappropriate ones. Really you need to design your production around your model, and more experienced models are simply more efficient at adapting themselves to what's in your mind, as long as you are also skilled at expressing that. If you imagined a photo is a film placed into one frame, then the photographer is (aside from the cameraman) the equivalent of the director and needs to know how to work with both experienced and inexperienced models and play to their strengths.
Now I sure can talk for my own lack of experience but between working with someone experienced (Yvonne, my girlfriend) and inexperienced (above) I find the biggest challenge while shooting is knowing what I want and expressing it clearly and efficiently so that the model can perform optimally.