Selenium should not be used to prepare a test case. All repetitive actions and preparations for a test case, should be done through other methods. For example, most web UIs have authentication (e.g. a login form). Eliminating logging in via web browser before every test will improve both the speed and stability of the test. A method should be created to gain access to the AUT* (e.g. using an API to login and set a cookie). Also, creating methods to pre-load data for testing should not be done using Selenium. As mentioned previously, existing APIs should be leveraged to create data for the AUT*.
*AUT: Application under test