IMHO if one learns the basic principles of Aikido such as maintaining proper distance from an adversary, avoiding conflict, being aware of one surroundings, then more than half of the self defense issues are taken care of. And yes this applied to pretty much any martial art in some form, but with Aikido these prinicples are streesed more often and probably more important. For example if you do not maintain proper distance the Aikido technique may not work well or at all.
BTW everyone asks this question, however the vast majority of people will never need self defense tactics if they just maintain an awareness of their surroundings, and conduct themselves in a calm assertive manner. Not easy to do though!
Which reminds me of a story a read on a bicycling forums quite sometime ago. It seems that this cyclist got into a confrontation with an elderly motorist. The motorist followed the cyclist to his destination and then proceed to scream at the cyclist and tell him he should have run him over and so on. Here is the good part, the cyclist reached into his pocket and got out a pen and started to wirte on his arm, seeing this the motorist stopped his rant and asked the cyclist what he writing down. The cyclist response was I have written your license plate number on my arm with a message to the authorities stating that I have just been murdered by someone driving a car with this plate number. So it would be in your best interest for me to live until I get home. He said it completely diffused the situation, and the motorist begged him to remove the writing from his arm. No physical conflict, and the cyclist still did a great job of ensuring his safety.
