How can one ensure that converting HTML to PHP does not lead to unnecessary complications or inefficiencies in the code?

When converting HTML to PHP, one should ensure that the PHP code is integrated seamlessly with the HTML markup to avoid unnecessary complications or inefficiencies. One way to achieve this is by using PHP's echo or print statements to output dynamic content within the HTML code. By keeping the PHP code organized and concise, it will be easier to maintain and debug in the future.

<!DOCTYPE html>
<html>
<head>
    <title>Welcome</title>
</head>
<body>
    <h1>Welcome <?php echo $username; ?></h1>
    <p>Your email address is: <?php echo $email; ?></p>
</body>
</html>