Get a throw away laptop purchased at a computer/ham fest and run TAILS. Don’t install on the HD, just keep it on the thumbdrive, preferably one of these:
Create a new set of accounts that you only access from that image. If you are really paranoid, leave your cellphone at home and connect to the coffee house/hotel/library wireless from the parking lot out of sight from the cameras.
What Hxtr alledges regarding the hardware may indeed be true. I understand that certain agencies have a special Windows 7 build and CentOS 7 builds for their internal use. TAILS obfuscates MAC addresses, but some identifiers that I outlined in some of my other posts are still there and may be mined and sent. Watch out for any computers/laptops/servers that have build in management interfaces. Those are notoriously suspected of being used for covert channels.
Sic transit InfoSec,