Steps

1. Never carry too much for too long unless it is necessary.
2. Walk with a sense of purpose. If you are wandering aimlessly or look lost you become a target.
3. Act and dress like a local. Tourists are frequent targets of muggers.
4. Carry a walking stick or a long, heavy item you can use in defence
5. Carry a weapon where it is permitted. Pepper spray, a 4 inch lockback pocketknife, or a pistol (9mm or 38 caliber minimum for stopping power) will give you confidence that muggers will sense and steer away from. This of course assumes you know how to use your weapon and are carrying it in such a manner that it is unlikely it can be used against you.
6. Learn a martial art, at least the basics. In cases where weapons are not an option, you need to know you can defend yourself with your hands and feet (and head) if necessary. Your confidence radiates outwards and protects you from feral humans who can sense fear.
7. When you sense danger, don't be afraid to act a little crazy. Walking down the middle of the street, and/or singing a song at the top of your lungs will make you a less attractive target. This contradicts the above advice of "not drawing attention to yourself", but when it seems that the attention is already there, it's time to act to discourage action.
8. Determine the risk factor of you getting mugged or robbed. These are the things that let you outweigh your risk of being robbed.
   • Clothes: Are you dressed like a rich person? Do you have fancy jewelery? Are you wearing a T-shirt and jeans or a suit?
   • What you're carrying: Are your hands empty or are you carrying a briefcase, backpack, or suitcase?
   • The area you are in: Is it an urban area with a lot of foot traffic, or a suburban neighborhood with few pedestrians?
   • How long you will be traveling: The longer you are on the streets, the higher the odds of you passing by at least one thief.
     
• Tips
  • You can put some valuables in your shoe or lining of your jacket.
  • If someone asks the time, don't check your watch or mobile phone. Asking for the time is a classic trick used by muggers to distract victims and locate valuables. Looking down or putting a hand in a pocket leaves you vulnerable to punches and other attacks.
  • Act casual when you walk, don't look anxious.
    
• Warnings
  • There is no surefire way to prevent theft.