A live distribution like Tails is the fastest and easiest way to a secure operating system. All you have to do is create a bootable CD or USB drive with the files provided and you’re set. Everything else will be preconfigured for you.
A virtual machine (VM) image like Whonix is designed to be run inside of a virtualization package like VirtualBox. VirtualBox can be installed on Windows, Linux, macOS, and Solaris. This means that if you're stuck using Windows or macOS for whatever reason, you can install VirtualBox and use Whonix to increase your privacy and security.