Matt Haughey's got a blog post called A Guide to Using Signal for Government Workers, but it works as a guide for anyone and spells out in a simple-to-understand single page why you should be using Signal.
If you don't know Signal, it's like WhatsApp except it's run by a non-profit, not a billionaire (WhatsApp and Messenger are owned by Facebook). It's a free communication app that works world-wide and runs on Android, iPhone, iPad, and Mac desktops. Unlike Apple's iMessage Signal messages are always encrypted, which means no one (not even Signal) has access to them and they're therefor subpoena-proof.
Free. Encrypted. No billionaires or nasty corporations.
