How can PHP developers ensure that their code is efficient and maintainable when working with variables and values?

PHP developers can ensure their code is efficient and maintainable by following best practices such as using meaningful variable names, avoiding global variables, using proper data types, and organizing code into reusable functions. By adhering to these principles, developers can write clean, readable code that is easier to debug and maintain.

// Example of using meaningful variable names and proper data types
$userName = "John Doe";
$userAge = 30;
$userEmail = "john.doe@example.com";

function sendEmail($email, $message) {
    // Function code here
}