Here are some great sources on how to improve digital storytelling skills:
This article from Big Spaceship outlines 9 aspects of the Star Wars films and why they were successful. The article then gives tips on how the reader can use these strategies to make their own digital storytelling more effective.
This article from Black Enterprise is focused more on the social networking side of digital storytelling. It talks about tagging, hashtags, website bios, and other tools that can help bring more people to your site or video to see your story.
This post from Jeff Bulas talks about how to make your content “sticky”. The author focuses on how to make your ideas memorable and shareable and then gives some general guidelines to follow for content generation.
This site is actually an aggregator of a bunch of different resources for digital storytelling. They regularly update their site and link to videos and articles that give tips on digital storytelling.
This article on Digital Learning Environments gives some suggestions about what to stay away from when attempting to tell a story digitally. It also gives some great tips about how to make your story effective.