I would enforce a policy for all my employees to use strong passwords that would make it more difficult for any outside forces to access sensitive information within the company. Alongside using strong passwords, I would require all employees to use a two-factor authorization token such as sending a text to their phone or scan a QR code that is exclusive to their accounts. I believe these are the two easiest, but strongest methods of protecting the availability of my systems because it would allow for easy accessibility for employees, but make accessibility increasingly difficult for outside users.