1. Generous function level and inline comments that explain the rationale behind code organization / approach. Code can be self-documenting, but intentions are not. A great programmer will ensure future maintainers / contributors don't break something for lack of understanding the original context.

2. No magic configurations. No implicit behaviors. Every optional behavior should be explicitly opt-in or opt-out.

3. Treat one as a special case of many. You will thank yourself later when you would otherwise curse the day you were born.