I keep my hair extremely short as a preference. Having one less thing an opponent can manipulate + cause you pain by is a nice benefit. However, I think this is predominantly a female hazard. Every single street fight I have ever seen with two women always comes down to the winner being able to manipulate their opponents hair, and punch them in the face whilst doing so. Short of shaving your heads, ladies, the only other thing I can think of to help you is braiding your hair, and that wouldn't be 100% effective.