It's not that difficult to train this skill.
- Get yourself a heavy bag.
- Throw left hook, right hook as fast, as powerful as you can "like a mad man". Don't stop until you get exhausted.
If you train like this for 3 years, you should be able to handle yourself in normal SD situation.
"Like a mad man" is the key word. If you are a mad man, people will be afraid of you and stay away from you. They will worry about how to defend themselves against you instead.
So the short cut for SD is to develop a single skill that you can use it to scare everybody away.
This is my favor "mad man attack" example. Instead of using left hook, right hook, he uses jab, cross.