Make testing a priority
When I started studying software development, every month I felt progress. But it came to a moment when I stagnated. I could already build anything I wanted. Still, I felt I was a kid in programming.
Then, I heard about test-driven development. It seemed a cool idea nobody followed. I gave it a try. Finally, here is something that made me feel more productive.
It takes some time to get used to. But then, it will change the game for you.
You can just refactor every piece of the code knowing that it won't break it in a significant way.
You can sleep better.
TDD separates boys from men; good work from bad.
When writing any piece of software, make testing a priority.