OPSEC 101 Guide - https://github.com/BushidoUK/Operational-Security-101
MFA applications - https://www.microsoft.com/en-us/account/authenticator
Safe browsing - https://www.browserling.com/
Malicious URL checker - https://urlscan.io/
Malicious file checker - https://www.virustotal.com/
Breach exposer https://haveibeenpwned.com/
Password manager - https://keepass.info/
Email alerts - https://www.google.co.uk/alerts
Twitter alerts - https://warble.co/
Secure email - https://protonmail.com/
VPN - https://protonvpn.com/
VMs - https://www.virtualbox.org/
Secure messaging & file transfer - https://keybase.io/
Intruder alerts - http://canarytokens.org/generate
So, you want to be a darknet drug lord... https://pastebin.com/GrV3uYh5
General Operational Security Resources - https://greysec.net/showthread.php?tid=2859