Tips to avoid being mugged

I am back from Lima, my last stop in Peru, but these were on my mind while I was there: 

1. Stride with confidence and purpose, even if you are utterly lost.
2. Carry a glass bottle, a coke bottle is best (it must be non-alcoholic).  Occasionally, take a drink as you stride towards your "destination."  The bottle makes a handy weapon but, unless it comes to the worst, I do not advise that you use it (just give them your money).  The muggers, however, don't know that.  Deterrence is your best defense.
3. If you are lost or in trouble then ask someone for help.  But if some Joe on the street asks if you need help say, "no thanks," and continue to follow rule 1.  The selection effect makes all the difference.
4. Do not walk in unknown areas, especially at night.

In my experience rule 4 works the best but it too has its opportunity cost.