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I still find writing quite a clumsy and difficult activity, but Paul fantastically articulates how to write effectively, which in this instance is about being useful.
If you narrow the topic sufficiently, you can probably find something you're an expert on. Write about that to start with. If you only have ten readers who care, that's fine. You're helping them, and you're writing. Later you can expand the breadth of topics you write about.
As in most cases, the best advice is often the most obvious one.