A girl's hair style says a lot, in my opinion. First, it should always be a hairstyle that looks good on the girl (this seems obvious, but a lot of girls have hairstyles that don't fit them).
The biggest thing a hairstyle indicates to me is a girl's mood. If she has it extra straightened or curled and done up, then it shows that she's in a fancy mood or looking to go out. If she has it done up in a pony tail, she's likely in a more laid back mood. It may not be true that they're actually in different moods, but it definitely gives the impression that they are. An extremely well done hairstyle is intimidating, whereas if a girl has her hair up in a bun she seems more down to earth and approachable. I think it's good for a girl to do a bit of both.
Hair is sexy and as long as it isn't really short (guy length short and not bob short) and it looks good with your face structure and body, I like it. I used to love long hair but recently a couple girls I know cut their hair relatively short and they look hotter than before.
Well I think my hair turn on 's would be long doesn't matter if strait or wavy, and I kinda like the idea that more and more girls are painting their hair with rad colors like blue green and shocking pink.
I just wear my hair however, if it looks good with my outfit, I'll do it a certain way. If I'm just doing an errand, I'll just tie it up and go. If you do hair styles that look really, outstanding, and you're meeting up with a guy, they'll think you're trying to hard and have a bad impression of you.