This is a new topic, yet for a female is extremely important and comes from several situations in which I think a good deal of vigelance needs to be maintained. While shooting San Francisco from Treasure Island at about 5 AM a couple years ago, a van pulled up and a gentleman got out and started a conversation. Needless to say, I had one eye on him and the photo became the second topic in my mind.
When shooting at night in city streets, I allow a six to eight foot area around me and when someone enters this, I ask them to stop and come no closer. In my left hand is an LED flashlight on a cord, the right hand has the camera and lens with the neck strap around my wrist in such a way I can swing it and take someone down or severely slow them up.... admittedly the camera and lens could be trashed but my life is worth more.
Another technique is to have another person watching my back, even an off duty LEO. I love dark alleys, city streets late at night and other places where some interesting shots can be obtained. But the need to protect me and $$$ equipment is essential.