If you know nothing about a topic when you start writing about it, use the writing process as a way to locate just enough of a toehold in the subject so that you can ask a good question that advances the understanding of the subject you are addressing.
The lazy blogger finds that someone else has done a thorough job of writing up an event or a subject, and tries to rewrite someone else's work as their own. The diligent blogger treats any account, no matter how detailed, as just the starting point for asking some question not previously anticipated. There is always some way to advance the story, even if it's only at the periphery.
What questions are left unasked? There is always one more thing to say.