> But improving one's writing is seemingly impenetrable, to me. I read what I write and it sucks but I have zero intuition about how to un-suck it. I fucking wish I could write like Heller, or Didion, or Tolkien. Not even in terms of writing novels but just the quality of their prose.

In the beginning it's great to practice your art by yourself with lots of safety, but sooner or later you're gonna want to to ask the public/community at large what they think of what you do, so you can get external feedback from people other's who love the same thing. I think this is probably the only way to actually get better, you need to connect with other people around it, and get their point of view. I've found this true for any creative endeavor I've tried to get better at.

Receiving criticism is probably as hard to get good at as giving criticism, so don't let the harsher stuff get into your skin as some people aren't so good at giving criticism, but you'll find lots of other useful advice that you'll agree with, and find directly actionable :)