There's no really other way to learn writing than by...

There's no really other way to learn writing than by writing. So accelerate that as much as you can. The more you write, the better you'll get. What also helps, though, is walking away from broken stuff. Not everything's going to work. Killing two years of your life trying to resuscitate a dying novel, I don't know. Why not just write a different one? You'll have more ideas. You can't help having ideas.