Using the DVD image in a VM would largely suffice for most users. For even more security, you would use the live image on a throwaway laptop at a coffee shop or something, but that's not exactly practical for everyday use.
I remember I used immutable VMs for a lot of testing - those reset to the last saved state when shut down and made a lot of tests more easily repeatable. This is a sensible thing to do for privacy as well - any cookies you gain during your session you shed on reboot.
And also Whonix: https://en.wikipedia.org/wiki/Whonix
Using the DVD image in a VM would largely suffice for most users. For even more security, you would use the live image on a throwaway laptop at a coffee shop or something, but that's not exactly practical for everyday use.