Being a woman the whole “personal safety” thing is different in ways most men don’t give a second thought. So while my comment may or may not apply to you, I do understand the basis of your concern. The Cell Phone idea is good, and if you’re comfortable actually using a gun if needed than I would trust Banshee’s advice. Although, I think the best defense is simply being aware of what (and who) is around you. When I’m traveling alone and see a gas station that is well lit and busy, I’ll stop and fill my tank even if I’m only down a half. It’s better than needing gas when I’m in an area that makes me nervous. (Yes, I know this next one sounds stupid but…) I try to not look like a walking target. When I go to and from my car I walk head up, shoulders back, like I know exactly where I’m going and pity to anything that gets in my way. Had one friend call it my “tough city b***ch” walk.
Bottom line..do what is within reason to stay safe, then relax and enjoy your trip.