What best practices can be implemented to address the issue of session variables not being cleared in PHP?

Session variables not being cleared in PHP can be addressed by explicitly calling `session_unset()` to clear all session variables when they are no longer needed. Additionally, calling `session_destroy()` can be used to destroy the current session. It is important to ensure that these functions are called at the appropriate points in the code to prevent session data from persisting beyond its intended lifespan.

// Clear all session variables
session_unset();

// Destroy the current session
session_destroy();