Best Practices for Unlocked Packages

We suggest that you follow these best practices when working with unlocked packages.

We recommend that you work with only one Dev Hub, and enable Dev Hub in a production org.
The Dev Hub org against which you run the sf package create command becomes the owner of the package. If the Dev Hub org associated with a package expires or is deleted, its packages no longer work.
Use care in deciding how to utilize namespaces. For most customers, we recommend working with no namespace or a single namespace to avoid unnecessary complexity in managing components. If you’re test-driving unlocked packages, use a test namespace.

Use real namespaces only when you’re ready to embark on a development path headed for release in a production org.

You can’t install a no-namespace, unlocked package into any org with a namespace (for example, a scratch org with a namespace).
Note
Include the --tag option when you use the sf package version create and sf package version update commands. This option helps you keep your version control system tags in sync with specific package versions.
Create user-friendly aliases for packaging IDs, and include those aliases in your Salesforce DX project file and when running CLI packaging commands. See: Package IDs and Aliases for Unlocked Packages.