Practicing good email hygiene is a bit of a technical voodoo art. Some smart behaviour can prevent viruses, spam, blacklisting, and other terrible things.
It includes things like
- Don't give out your email address too often and in public places
- Don't share your password
- Don't use the same password on different accounts and services
- Use complex passwords (there are lots of opinions about what a complex password is)
- Change your password occasionally, or possibly your email address too.
- Don't use an obvious email address (i.e., avoid accounts@ info@ and admin@ etc.)
- Have separate throw-away email address(es)
- Don't subscribe to dodgy services.
- Have an SPF record in DNS to help prevent email spoofing (I can help)
- Use a spam blocker, info: https://support.enlightenhosting.com/hc/en-us/articles/360029922692-Spam-blocking
- Use a virus checker
- Use an inbox rule. tip: https://support.enlightenhosting.com/hc/en-us/articles/360032813411-Custom-inbox-rule-webmail
- Learn how to spot suspicious emails
- Check before clicking links, or opening documents in emails
- Check with and subscribe to to breach services (I can recommend https://haveibeenpwned.com/ )
- Keep your desktop and other devices secure
- Follow other general email best-practices -(some tips here: https://support.enlightenhosting.com/hc/en-us/articles/208175186-Email-best-practices )
- Consider Spear-Phishing and Whaling https://www.cert.govt.nz/business/common-threats/protecting-your-business-from-spear-phishing-and-whaling
- Use a different email address for any marketing
- Don't send marketing messages with lots of CCs; use separate messages.
- Use a professional email marketing platform (such as mailchimp) rather than your own email system for bulk mail-outs
- Follow anti-spam law: https://www.dia.govt.nz/Spam-NZ-Spam-Law-for-Businesses and http://www.legislation.govt.nz/act/public/2007/0007/latest/whole.html#DLM405198
I'm sure you can google more and different advice, it's a bit of a balance between usability and security and there are lots of opinions.