For free flying hair, experimentation. If it is bound in any way, you might want to get one of Harvey Mann's hair props and examine it closely. He only uses the dynamic hair for things like ponytails and bangs, and free flying tendrils about the ears. The rest of the hair is actually transmapped (and since it is hair that is pulled tight due to -being- bound, it works just fine). It saves some time...and frees up resources to make the stuff that actually does move thicker and more lifelike.