I think that self-defense probably starts with common sense about trying not to put ourselves in a bad situation to begin with, although admittedly, we can't always control every situation.
Does anyone remember seeing that detective who was on Oprah Winfrey's show many years ago saying what you should do if you found yourself in a bad situation? I always found that pretty helpful.
Two situations I can think of right now for myself that were a little hairy (no pun intended!):
When I was in junior high, a friend and I were near a park when a guy came up and exposed himself to us
classic trench coat and all. I don't think you ever saw two kids hop on bikes faster! And we rode as fast as we could probably a mile before we slowed down!
Another time, I was in college, with a friend, studying on an isolated beach. It was that time of year where it was one of the first warm days, so early in the season, probably late March. Nobody else was around as far as the eye could see. We took my German Shepherd along and had his long rope tied to the back of my Jeep. Out of nowhere we noticed a sketchy-looking guy coming up towards us. The dog was quietly watching him, too. My spidey sense was that he was up to no good. Anyway, when the guy got closer to us, the dog suddenly lunged at him, coming to the end of his rope and actually flipping up in the air, snarling. Fortunately he came close to, but didn't touch the guy. I had never seen my dog do that before, and was pretty taken aback. The guy said, "Whoa", put his arms up, looked around at our belongings, then walked away. I was never so glad to have had my dog with me as I was that day. I later learned that there were some homeless people living in the dunes on this beach.
Both were public places. I never went down to that beach again when nobody else was around.