When I started to realize the value of storytelling, I gathered a group of friends to meet regularly to improve our storytelling. I read a bunch of books on storytelling and distilled their essence into a few parts -- mainly characters, conflict, struggle, and goal, which I memorize as CCSG. All the books I read described these four elements as the most important, which my experience confirms.

I wrote a few posts on the basics of storytelling (not all independent). While no substitute for practice, observing, and reading comprehensive books, people have told me they helped improve their storytelling. Storytelling improves persuasion and a lot more.

http://joshuaspodek.com/model-great-story

http://joshuaspodek.com/communication-skills-exercises-4

http://joshuaspodek.com/improve-public-speaking-storytelling...

Speaking of practice, look up http://themoth.org for great storytelling events and podcasts. The Moth is amazing. (If you search my blog you can find video of me telling stories at the Moth).