This is just a quick first draft to record some things I have learned in recent days.
I have created and tested three templates as of today.
The first is to play with custom CSS and see how the system works.
The second is a preparatory template for the next TAD Table of Contents.
The third is for sending out short notices such as requests for payment of dues and information about conferences.
The templates do occasionally need to be tweaked and tested, but in the ordinary course of producing an email to be sent to a subscription list, begin with Components / AcyMailing / Emails to start a new email campaign and edit the body of the email, not the template.
Please do not edit past email campaigns. That destroys the evidence of what worked in the past. Instead, send yourself a test email from a successful campaign and use that for guidance in creating a new campaign from scratch.