How can I troubleshoot SQL Server authentication errors 18456?

Troubleshooting involves several steps. First, verify the username and password for typos. Second, check if the SQL Server login is enabled. Third, examine the SQL Server error log for more detailed information about the authentication failure. Fourth, ensure the user has been granted permissions to connect to the specified database or server. Fifth, check the SQL Server's security configuration to ensure the login is allowed to connect from the client's IP address or network.