Cold storage, f.e. Electrum Offline on X(L)ubuntu.. You have to make bootable pendrive ()ubuntu version installed via virtual machine, or other pendrive, than send installation files tu ()ubuntu and boot your computer from this pen without turning data connection on.
On your personal computer you can generate transaction and in offline linux you can signing it..

You may generate paperwallet in  bitadress: https://github.com/pointbiz/bitaddress.org but turing it in offline system is a good practice, too

And paperwallet is less comfortable...