I hate those articles that promise to tell you the One Single Reason X Was Successful — those are always bullshit, because there’s never a single reason for anything. When you try and find one, you’re trying to tell a story rather than state the facts.
All you can do is improve. Constantly improve. And the one, single way to do that is to set whatever you’re working on loose, gather feedback and try again. You repeat this process every time you make something, and sooner or later, you’re going to get better.