Tightly control access to your Azure Repos to prevent unauthorized access and maintain the security of your application's source code. This includes mandating that users never share accounts or passwords, securing laptops and devices with access to source code, managing team access to data, revoking access from former employees, and ensuring proper revocation of Azure Repos accounts when users leave the company. By following these best practices, developers can ensure their application's security is robust and up-to-date.