To make clear right away: this is NOT an article on how to fight.  This is an article on how to not NEED to fight.  Techniques on how to disarm maim or kill will not be covered.  No flashy folding knives, “tactical” flashlights, kubotans, fistloads, or knuckledusters will be discussed here.  These are all weapons (tools you use offensively), or offensive techniques, and this is an article about defense.  A weapon is a tool for harming another human being by offensive action.  Is there such a thing as a “defensive” weapon?  Likely not, unless you want to split hairs about shields, which you carry to a medieval battlefield, not every day on your usual rounds.  This is a discussion on situational awareness and how to carry your self (aka. “street smarts”), to discourage and minimize the possibility of getting in a confrontation. 

Your author, it should be mentioned, is NO great street fighter, warrior, martial artist, or psychology expert.  Training in these fields he HAS had, but the following ideas are gleaned from walking into and out of some shit more or less intact.  If you’re in a rowdy bar, bad part of town, or walking a country road when the banjos start, it will seldom be immediately obvious what kind of situation you’re in, or what the perfect response is until after the fact.  Perfect responses don’t matter.  If you walk away free and unhurt you did it right.
DO:  Take these ideas, incorporate and use as they make sense to you. 
DO NOT:  Replace entirely how you conduct yourself with this advice.  Even the schmuck writing it doesn’t consider it definitive.

Step 1: Awareness.  Know what’s going on around you, that simple.  Keep eyes, ears, and mind open.

If there’s a part of town where people get rolled for having the wrong skin color, guess where you shouldn’t go.  If you see or hear police getting ready to sweep and area, or a group starting to argue / fight, it MIGHT be good to make your way elsewhere.  Information heeded in time is easier, cheaper, and safer than bullets when things go bad.

Step 2:  Don’t look like a target.  Unless someone has a personal reason to harm you, they usually are NOT looking for a fight.  They are looking for an easy target.  There are always exceptions, but most muggers, pickpockets, etc, only want to hit a mark and get away unscathed.  Looking like a hard target will dissuade many problems.  Being tall, wide, or male helps right off the bat, but looking cognizant and ready can be done by anyone regardless. 

Keep moving confidently and steadily, like you are supposed to be where you are and know EXACTLY where you are going.  RELAX; holding your shoulders or arms tensely is an easy way to signal nervousness.

Though you should be aware of surroundings, use more senses than your eyes.  Constant backward glancing and head swiveling looks nervous and unsure.  Eyes forward, head slightly down, just keep on trucking.  Use eyeglasses or glass storefronts to check what’s behind you. 
Wear clothes you can move in, and shoes you can run in.  Avoid ANY kind of shoe which makes a nervous “TAP TAP TAP TAP” sound when you try to walk faster. 
Don’t take out your wallet, phone, or anything expensive if you’re unsure of the surroundings.  People like to steal things that hold money or cost money, so don’t let them see that you have them. 

Try to avoid any action which would take your attention off of your environment.  (Rummaging through a purse or bag to find a lighter for someone who asks you for one, for example.)  Not always possible, but having your face glued to your phone / map / iPod is a GOOD way to look vulnerable.  (If you decide to wear headphones, learn to adjust the music and volume when the player is in you pocket.) 

If you need to carry a bag, wear it across your torso, or high and tight on your shoulder.  Carrying one loose on the lower arm, on one shoulder, or held in the hand makes them a PRIME candidate for a run – by snatching.

Step 3: Aversion.  A good glare will get you out of more situations better than fighting. 
If you can’t or don’t want to try a staring contest, you can always be gross.  Sag forward and drool in a train seat, hack up a lung, talk like a retard, rant to yourself, VOMIT, shit your self, (as the situation warrants, of course).  Most mugger / rapists do NOT want to deal with this.  Most regular folks will get disturbed and stay away too. 

Step 4:  Get out of Dodge.  If you know you’re being followed, suspect it, or even get an attack of the “Spider Sense”, make your way to a more populous area.  Call the cops or a cab.  Again, move purposeful and steady.  If you must, RUN.  Yes, it signals panic, and may encourage the pursuer to give chase, but if you can reach a safe place fast, it works. 
If confronted with a gun or a knife, handing over your cash is MUCH cheaper than medical bills.  Give (Read: toss your cash), to the shithead, back off, and RUN.  Keep credit cards and ID separate from money.  If you’re carrying BIG change, keep it somewhere away from your pocket cash.