But you know what?
It doesn't matter. As long as I'm making sense and my copy has a smooth flow...its all good. I've come to understand that the goal of my copy is to grab my customers attention and lead him straight to the buy button.
You have to understand that everything you write is leading the customer to the next sentence and eventually to the "Buy now" button. You have to be persuasive, But you also have to "lead" him through your copy.
The role of every sentence you write is to lead the customer to the next one. So just write whatever the heck you want to without aiming for perfection and preferably, as a letter to your ideal customer profile.
Once you're finished, you can go back to your "crappy" draft after a day or two and edit it until its clear, concise and gets your message across without any kind of confusion.
Its like driving a car, it starts coming to you naturally after a while.
I know there are people out here who doubt if they'll ever be able to write good copy. You spend thousands on courses and never write a single word of copy because you always seek perfection. Have you ever seen a letter consistently pull in a 100% conversion rate? I haven't.
You can write the crappiest letter in history.. revise it and turn it into a winner. You just need to get your foot in the door.