How Do You Know If Your Copy Is Any Good? (My 5 Step Process For Copy Testing)

For the sake of argument, let’s say you know the basics of copywriting.
Blah blah, write a compelling headline, know your audience, be persuasive, find your unique selling proposition, keep copy clean, blah blah blah.
At one point, this advice was great. But from where you’re sitting, “write compelling headlines” isn’t helpful anymore, is it?