What CI/CD best practices are you familiar with? Or what do you consider as CI/CD best practice?

Difficulty: unrated

Answer

Commit and test often.
Testing/Staging environment should be a clone of production environment.
Clean up your environments (e.g. your CI/CD pipelines may create a lot of resources. They should also take care of cleaning up everything they create)
The CI/CD pipelines should provide the same results when executed locally or remotely
Treat CI/CD as another application in your organization. Not as a glue code.
On demand environments instead of pre-allocated resources for CI/CD purposes
Stages/Steps/Tasks of pipelines should be shared between applications or microservices (don't re-invent common tasks like "cloning a project")