Awareness is the first step to self-defense. You can't live your life expecting a problem, but you have to train yourself to be more alert and elevate your level of awareness of your surroundings.
A self-defense course can empower you with a few techniques and ideas to interrupt an assault long enough to escape. There are no guarantees. Anyone can be victimized even if you have taken a self-defense course. Once you’ve completed a self-defense course it’s up to you to put the information you gained to work for you in your day-to-day life.