How Do You Write a Blog or Podcast?

Ross akof the great system thinker tells a story of being asked to help out a school that was having an enormous amount of trouble with literacy. He made a simple suggestion, get old charliey chaplin movies and let kids who wanted to drop out of class sit there and watch them. Within weeks, the kids started to figure out what the subtitles said, ecause the movies were better ones they knew. The idea is that properly motivated humans learned stuff all the time. And i'd like to ask, when you write a blog or record a podcast, do you pick the topic first and then research the content too? Or do you read and re search so much that the topic will