Practice Writing
To achieve mastery of any skill, the conventional wisdom goes, you have to practice that skill for ten thousand hours. And practice doesn't just mean “do that thing”, it means focus on building that skill.
When we talk about practicing a musical instrument, we've got a good idea of what that looks like. My kids spend half an hour every day practicing the piano, playing songs that their piano teacher assigned them. Their teacher assigns these songs based on their current skill level, and they are calibrated to stretch the students' abilities, to be just a little harder than the students can comfortably play.
And once my kids are done playing their songs, the songs are gone, dissipated into the air around the piano.
But what about practice writing? When I work on the skill of writing, I end up with lots and lots of random little files called things like free write Tuesday, October 30, 2018.md. or random story about fish.md. Or, well, blog posts like this.
Some people, of course, end up with notebooks full of their words. Tolkien famously used the same paper notebooks over and over, erasing them when they were full and filling them again. His son Christopher has spent a lifetime going through those notebooks, figuring out what the erased versions said and publishing those erased stories.