A pony tail belongs to very confident women, who are known to be bold between the sheets. The gesture of opening up the face, instead of hiding behind bangs, or hair in general indicates their self assurance.
Always styled hair, even at home, is a sign of a woman who likes to control things and live in order. She's probably happiest when orchestrating events, and even bed sessions.
Wild, free hair indicates that a woman is free spirited (just like the look implies, bohemian), conmfortable in her own skin and is down to try anything.
A messy bun is worn by someone who craves glamor, elegance and romance. The exposed neck being a very erotic spot indicates that she is flirty, open to contact and enjoys male attention.