Know thine API; don't constantly reinvent the wheel

Knowing the Drupal API is an insurmountable task. Referencing it anytime you think you might need to is an encouraged best practice. Don't try to combat a series of programming tasks with brute force coding skillz. Instead, anytime you feel that you're writing more functions than normal, stop and reference the core API docs for potential way around your problem. If you are working with contrib modules, browsing the contrib module code might be helpful.

Let's face it. You're smart, but it's really good odds that someone else in the world has tried this before, and then written it into an API. It might be a single function in the API, or it might be a series of functions that you'll need, but since one of the goals of good coding is future-proof code, using the API at every opportunity will get you there.