How did you turn what you know into something people actually wanted?

I have been thinking about how people take skills or experience they already have and turn it into something useful for others. I recently came across a site called BuiltToLaunch, which talks a lot about turning personal experience into something structured, and it got me thinking more deeply about the early stages.

A lot of advice online jumps straight into tactics, but I am more curious about the thinking part before anything serious happens. For those who’ve been through it, how did you figure out what to focus on first? What helped you move from an idea to something real? And if you were starting again, what would you do differently?

Not looking for shortcuts, just honest experiences from people who have already done it.