Two things that are important if you want to be a better developer:
#1 - Avoid Duplication.
As simple as that. There are very few excuses for duplication in code. Removal of duplication is important for so many reasons. Firstly, consistent behavior, secondly, better design. Yes, almost any attempt to remove duplication should move you into a better design position. And it allows you to improve your design easier if necessary. Do not repeat yourself. Do NOT repeat yourself.
#2 - Become a Better Tester.
Yup, a tester. I worked with a colleague years ago who was (and probably still is) a better tester than I. I helped her get her code working, as it was a bit of mess, but hey, we all do that sometimes. She tested it. Comes to review time and management love her. Me, not so much. Moral to this story: Code quality is important, very important, but being a better tester and a better dev makes you and your area work better. Management will love that.