please remember that my opinion and $ will buy coffee at the diner
1 first line of defense - know where you are at and what is around you, keep your head on a swivel and do not focus your whole attention on just one thing, including taking photographs
2 if you are planning on going to to the "wrong part of town" ask yourself the old WW II gasoline rationing question: Is this trip really necessary
http://www.fortmissoulamuseum.org/WWII/the-need-to-sacrifice_is-your-trip-necessary.php
3 your money/camera/credit cards, etc, etc etc or your life is an easy question to answer especially if you have insured your equipment give it up quickly, remember your goal, if things go south, is to survive, not be a hero or show off.
4 if all else fails fight with anything you may have - a set of keys projecting from your closed fist won't be as sharp as "Wolverine's" claws but may be helpful, aim for the face if you can
5 remember, the old combat strategy, kick him/her where you don't want to be kicked, put your hand behind his/her neck and introduce his/her nose to your knee and then run fast because all you have accomplished is to make him/her mad at you.