Okkkkk (PW takes deep breath before embarking on the road already well travelled):
Welcome to the forums for a start.
Based on your thread, what you want to learn isn't
self defence. It's fighting. You want to learn how to fight.
Self defence isn't
If you are in a bad situation (as you described, and it is pretty unlikely to happen in a 1st world country), you seem intent already on fighting. So you are imagining a scenario, getting scared by that make believe scenario ("getting mugged") and deciding that you are going to fight.
If this isn't the case, and you don't want to fight, well heres an idea... don't waste your time learning how to fight! If you are going to become a slave to your own fear, at least imagine yourself running away from the "muggers" rather than breaking their necks.
Aside from the whole issue of letting your imagination getting the best of you, you are unlikely to have much success learning to fight by yourself.
On a slightly more serious note, if you honestly want to learn about self-defence you have to educate yourself, not learn to fight. Below is a great place to start, it has some fantastic information on SD (and it has nothing to do with fighting):www.nononsenseselfdefense.com/
Also read about this:
It is a biologists observation of the "fight or flight" reaction to wild animals. Basically, and animal only switches the FOF reaction on when it is in ACTUAL danger. A lot of the animals other systems shut down. This only lasts as long as the animal is in danger, or it dies. Either way, it only lasts a few minutes.
The jist of the book is Zebras don't get ulcers or other stress related diseases because they only use the FOF when they are in ACTUAL danger. They don't switch that stress reaction on when they are late for work, or when they get carried away by something they saw on the news or in the movies.
Like Prof Spolsky says, a Zebra wouldn't understand why an animal gets worked up because it is running late for work, or because it imagines things that aren't real.
So in conclusion, don't worry about fighting if you are serious about Self Defence. You can form a great and effective SD strategy without knowing how to fight. And don't worry about getting attacked. Its highly unlikely to ever happen (unless you are a Prison Guard or such like!) and if you educate yourself on actual Self Defence, you are reducing the odds a lot lot more.