Muggers will tend to look for people who appear to be an easy target so if you appear to be confident and aware of your surroundings then you are less likely to be attacked.

Exactly. I regularly walk around London alone in the dark, because it's the only way for me to do things I want to do - like LPC classes/Guides etc. I don't listen to music/radio while doing that, nor do I read a book or play with my mobile phone. I am aware of everything that's going on around me. I also don't look like a 'victim' - I know where I'm going and walk purposively.