What best practices should be followed when using submit buttons in PHP forms for data manipulation?

When using submit buttons in PHP forms for data manipulation, it is important to validate the form data before processing it to prevent any potential security vulnerabilities. Additionally, it is recommended to use prepared statements or parameterized queries to prevent SQL injection attacks. Lastly, always sanitize user input to avoid cross-site scripting (XSS) attacks.

<?php
if ($_SERVER["REQUEST_METHOD"] == "POST") {
    // Validate form data
    // Process form data securely using prepared statements or parameterized queries
    // Sanitize user input to prevent XSS attacks
}
?>