Writing is a skill you must practice to hone. If you practice badly, eventually you’ll get really, really good at being really, really bad. You get good at writing by practicing the right things, instead of just writing whatever comes into your head. To write well, you have to internalize the basic sound and feel of good writing—which is something you can do by rote copying of excellent writing models.
To do this: pick a writer you admire. Find some of their work, and copy it, either with pen/pencil in your writer’s journal or on the computer. There is evidence that the mechanical act of copying great models is the key to rapid improvement. Plus, it can be a meditative practice, as it asks us to settle in and be present with the words, which I, personally, love.
I took a poetry writing class during my PhD. I was the only student who had never written poetry. The other students? Heck, one of them had been nominated for a Pulitzer Prize in poetry! To get the most benefit from the class, I needed to get up to speed, fast! My methodology was simple: For writing practice, I copied the works of great poets. Every day, in my writing journal, on the left hand page, I would copy a poem or if the poem was really long, a passage from it. On the right hand side, I would write my own poem using the same style. By the end of the term, I was writing better poems that some of my class mates, and since then I’ve had a poem published and been an invited reader at two poetry readings. Does the method work? You tell me.