http://galaxy4ogmifzf2wwdkbedqeps7pzxa53bkluyszq6sqng4u5g5nixid.onion/blog/view/437/full-opsec-guide-for-the-new-guys-full-opsec-guide
Debian, Kali, Arch, Parrot, etc... are not enough. - When you are communicating during an attack first have a custom super long password for each other beforehand to encrypt your emails when you send messages then when you trade credentials for an onion chat hosting with onionshare. Make sure it is 100% randomized with extended ascii on the max length. Once you use it once, it is just for that one chat. - Signal is also another good option without the complication though...