In order to achieve End-to-End (E-E) test stability, it's essential to consider environment-agnostic testing and test data management. Environment-agnostic tests should be independent units that run without code changes or dependencies on other environments, using tokenized configuration information. Tools like xmlpreprocess.exe can help update app.config files with environment-specific values. For web applications, separate config files per environment can also be used to maintain a clean separation of concerns between test config and code. Test data management can be achieved through CRUD flow, generating and cleaning up data as part of the test setup, or using service virtualization tools like Wiremock or Mountebank to create virtual services that mimic third-party dependencies. By implementing these strategies, developers can improve E-E test stability and maintainability.