What best practices should be followed when writing PHP code to prevent issues with undefined variables?

When writing PHP code, it's important to always initialize variables before using them to prevent issues with undefined variables. One common practice is to use isset() or empty() functions to check if a variable is set before using it in your code. This helps avoid errors and ensures that your code runs smoothly.

// Example of checking if a variable is set before using it
$variable = isset($some_variable) ? $some_variable : null;