What are your software development principles?

I find myself coming back to this one

Ninety–ninety rule

In computer programming and software engineering, the ninety-ninety rule is a humorous aphorism that states:

The first 90 percent of the code accounts for the first 90 percent of the development time. The remaining 10 percent of the code accounts for the other 90 percent of the development time.

View on Wikipedia

The Debugging Paradox: The harder you push to find a bug, the more elusive it becomes. The moment you step away from the keyboard, the solution suddenly becomes clear.

"Always check your assumptions"
This comes into play best when debugging. Assuming an input has a specific value (or even a value at all), assuming a method is being called, assuming a library works as you think it does, assuming that your deployed code and configuration is as you expected it to be, assuming debug and release will behave the same in all circumstances...

1. Follow code conventions: Indentation, Case
2. Name variables/functions/classes appropriately.
3. Use small private helper functions.
4. Don't let error cases/ exceptions slide off quietly. Just log them.

Keep is simple...

Programming is very simple: you learn all the best practices, and then you forget about them and focus on what your colleagues and your customers need.

TDD
DDD
SOLID
KISS
DRY
Clean Code
Use design patterns if it's possible. Refactor if not.

It's very small and simple, but:

"Continuous Improvement: Feeling dissatisfied with your past code is natural and appropriate. It shows an understanding of your evolving skills."

"If I had eight hours to chop down a tree, I'd spend six sharpening my axe".

Always write agorithm before, you start coding. When you write, many problems becomes evident, which you can remove right there. Once it become satisfactory, it become too easy to code.