Writing a basic test before starting a task, and use that to verify that the task is correct. I use the word task because this can apply outside of writing code

Writing a basic test before starting a task, and use that to verify that the task is correct. I use the word task because this can apply outside of writing code, for example making some large scale changes to data. Never underestimate your ability to overestimate your ability. Reality is hard so make the machine help you.