Before you start
Start here
What this course is, what it is not, and why it is written for the operator rather than the copywriter.
This is the body of practice behind the Marketing endorsement. It is free, it is complete, and it is not preparation for anything.
It is written for the person accountable for how marketing runs, not for the person writing the copy. The distinction matters because most of what goes wrong here is operational rather than creative: the message is fine and nobody can tell, or the message is wrong and every number says it is working.
Run the Operator's Diagnostic first if you have not. It spans all eight domains and it will tell you whether marketing is where your problem actually lives. Frequently it is not, and the numbers that look worst are downstream of something else entirely.
Nothing here is required, nothing here is assessed, and reading all of it confers no advantage on anyone.
Two things worth doing, neither of which costs anything
Read the standard in full, free and in the open, before you pay anything or give anyone an address.