pesky'apostrophe: always better than an unexpected period.
Being 6' tall and a guy most people don't mess with me. I also keep aware when walking alone, so I can avoid a bad situation.
The karate teachers at the local community center used to offer a self defense class for women. They came in with all the pads (much like you see on TV) and hung paper over the windows so the women did not feel on display. With the pads the women could really hit, kick, scratch, throw, etc. the guys around. Lots of confidence building.
Even if you can't take a class, carrying yourself with confidence and being aware of your surroundings can go a long way to not having problems. It sends out a "don't mess with me" vibe that will push those that want to harm you away. If you are fearful, people will sense it and prey on it.