We have mentioned the National Cyber Security Centre (“NCSC”) before, and their very helpful guide on IT security.
The NCSC have recently added an updated guide on how best to avoid Phishing attacks and you can read it here. It includes a handy infographic which is here in .jpg format (their link to the PDF didn’t work when I tried it).
I would recommend that every organisation works through their checklist, and even considers implementing DMARC (see the article for more).