Shoot a quick screencast video… If you’re on a PC, use Camtasia. If you’re on a Mac, use Screenflow. These are tools to record what’s happening on your screen. You can use them to present slideshow presentations or give a tutorial on how to do something on your computer. For example, when I teach WordPress stuff, I turn on ScreenFlow and just record my screen as show people how to set things up. It’s simple.
Include social sharing buttons and an "Email to a Friend" button in your marketing emails. That way, you'll gain access to their friends, colleagues, and networks and expand your contact list. At the bottom of your emails, include a "Subscribe" CTA as a simple text-based link so that the people receiving the forwarded emails can easily opt-in, too.
For effective and actionable results, you should do A/B tests, which test two (or more) different approaches. For example, you could send half of your list one subject line, and an alternate subject line to the other half. You could also A/B test the two approaches with a small subset of your list, then send the winning headline to the rest of the list.