Well, dancing isn’t really the kind of thing I photograph either, so I wouldn’t know specifically. But I’d say you should feel free to be creative with it. In general, you want things to be sharp and clear, so I’d start at around 1/500. If that doesn’t capture the movement like you want, you can go faster. However, it wouldn’t hurt to see what would happen if you go slower. Like 1/100, or even down to 1/20. Some blur in the photo might actually look nice. As long as the shutter speed is fast enough to make sure the face is still sharp. That would be my suggestions.
