I was pretty naive back in college too. I would walk alone in the dark from the building where I worked all the way across campus to the parking garage.

I was always looking around me though, had my keys on a lanyard (and believe me, I had a lot of keys) and I would jangle them and swing them in a way that if anyone came towards me in a threatening manner, I'm sure it would hurt when I whip them around.

Thankfully no one ever bothered me.

I did take a self defense class, but it was so long ago, I probably don't remember any of the moves.