Collected wisdom. Some of it is pithy. Some of it is specific. All of it is helpful.

Automation

If your build pipeline produces an artifact (a docker image, library, binary, etc.) that you intend to deploy, run tests/validation on that artifact. If you run tests in a separate environment before building the final deployment artifact, you have no idea whether what you're shipping is broken, and even worse, you might convince yourself that it's correct when it isn't. This is usually a little bit more challenging than running tests in a separate environment, but you get much more certainty that whatever is going out the door is actually functional.

Clarity

Debugging is twice as hard as writing the code in the first place. Therefore, if you write the code as cleverly as possible, you are, by definition, not smart enough to debug it.

-- Brian Kernighan

Documentation

Consuming and producing documentation should not happen in the same place.

Producing documentation should happen close to the code, preferably in the codebase, itself. This allows for a low-friction workflow that doesn't add additional burden on engineers. However, others who consume the documentation almost never want to go to a repository to read it. Generate beautified HTML from your project's documentation and ship it to an easy-to-find webpage/wiki. You still have a single-source-of-truth, and both writers and readers are happy.