Hideez and Yubico are giving free security keys, such as Yubikeys and Trustkeys, to any journalist working in Ukraine. See Free security keys for journalists | Yubico Secure It Forward In Ukraine

Use Signal

Signal is a modern, end-to-end encrypted, forward secrecy, and privacy centric messaging app. It is used by journalists, activists, and dissidents around the globe. I does not store any personal information, or your contacts(Signal hashes contact info when used for searching). It is as well run by an independent non-profit, Signal foundation, so their entire goal is free, and privacy first secure communication.

EFF has wonderful instruction on how to use, and configure signal:

Whatsapp

Whatsapp has similar level of security when it comes to messaging, and uses the same secure encryption protocol as Signal, but has a lot more privacy issues, such as data sharing with Facebook, and stores full contact list on their servers. Additionally Whatsapp loves to ask for store plaintext backup of your messages on your Google Drive, or iCloud, which is really unsafe for journalists.

It is advised to use Signal over Whatsapp, but with some tweaks Whatsapp can deliver similar security.

EFF has wonderful instruction on how to use, and configure whatsapp:

Telegram

I think let’s first change the narrative about what Telegram is. Telegram is a social network. Same way you won’t trust Facebook Messenger with your most sensitive information, same you should not trust Telegram.