What's the best way to maintain consistency in Python package versioning across multiple projects?

The best way to maintain consistency in Python package versioning is with virtual environments and dependency management tools. So, create a separate virtual environment for each project using tools like `venv` or `virtualenv`, and isolate project-specific dependencies within these environments.

Of course, remember to use a "requirements.txt" file to specify the exact package version for each project. You should also consider using a package manager tool like `pip-tools` to simplify the dependency management process.