I've found that in some ways, the camera itself helps. Shooting mostly large format, toting around the big monster acts as an icebreaker. You can get the sitter relaxed by talking about the camera itself, how it works, what you do with it, and then getting in front of it yourself to let them see what you see. Often that's a big help, because once they see what you're seeing on the groundglass, it gets them thinking, and gives them a new respect for the work you're doing. I don't think this applies so much with smaller format cameras, since even medium format viewfinders project a right-side up image and they also "feel" familiar. Large format also has compromises, of course, but I think in the end they're worth it as they help engage the model in the creative process.
This is not to slight medium format or 35mm in the least- some terrific portrait work has been done and continues to be done in those formats. I think that they lend themselves to a more fast-paced and less interactive way of working. I'd be much more likely to pick up the Hassy if I were shooting a fashion shoot or an editorial project than I would for a portrait session, or for a nude project.
This is not to slight medium format or 35mm in the least- some terrific portrait work has been done and continues to be done in those formats. I think that they lend themselves to a more fast-paced and less interactive way of working. I'd be much more likely to pick up the Hassy if I were shooting a fashion shoot or an editorial project than I would for a portrait session, or for a nude project.