What matters to you?
Most people care about something. It may be something big—like world hunger—or it may be something small—like a local animal shelter. Big or small, what do you care about?
As a writer, you can use your gift (and your hard-earned skills) to impact those things you care about. Actually, you should. Not just for whatever it is you care about, but for you and your platform.
People like people who care, and readers are people. They don’t necessarily want to be hit over the head with your whole worldview, but caring about something doesn’t require a two-by-four. Put some of that caring into your platform and draw people in—not just to the issues that matter to you, but to you. By showing people what you care about, you show yourself. It’s part of relationship building and that’s the basis of any platform.