I saw a show about self defense for women in NY city. The instructor said to always carry a sucker. One of those tootsie pops or the like. If in trouble, hold the ball in your hand, turn the stick outward, between your middle and ring finger and punch at something soft and fleshy like stomach or face (eyes, mouth). It's nice because it works everywhere. Even the TSA will let you board a plane with a sucker.