Are there any common pitfalls to avoid when trying to secure PHP scripts?

One common pitfall to avoid when trying to secure PHP scripts is failing to sanitize user input, which can leave your application vulnerable to SQL injection attacks. To prevent this, always use parameterized queries or prepared statements when interacting with a database.

// Example of using prepared statements to prevent SQL injection
$stmt = $pdo->prepare('SELECT * FROM users WHERE username = :username');
$stmt->bindParam(':username', $username);
$stmt->execute();