Well first off, I'd make a commercial where a kid is watching a generic caped superhero (kinda like a Superman ripoff) on a black and white TV. While he's watching it, he gets bored to death. Then the announcer will go, "Tired of the same old superheroes?" And then comes several kickass action and drama clips from KRDK in HD, implying that it's a more intense and more serious show.
And at the end, it'll say "Kamen Rider Dragon Knight! Now available on DVD and Blu-ray."