What are the best practices for securing PHP scripts and preventing unauthorized access to sensitive information in a shared hosting environment?

Securing PHP scripts in a shared hosting environment involves implementing measures to prevent unauthorized access to sensitive information. One way to achieve this is by using .htaccess files to restrict access to certain directories or files. Additionally, it is important to sanitize user input to prevent SQL injection attacks and validate user permissions before executing sensitive operations.

// Example of using .htaccess to restrict access to sensitive files
deny from all