the secret to all persuasive writing
It's a bit of an oversimplification, but not by much. The secret to strong persuasive writing is that there is no secret. Persuasive writing is really quite simple. Want to be a great persuasive writer? It comes down to just one word:
Lawyers and other persuasive writers nearly always write to complete a task or a component of that task, they write without thinking about why they are doing it. Lincolnesq calls it "Checkbox Writing" - you write a Preliminary Statement, Statement of Facts, Legal Argument, Conclusion, and so on so you can check off each of those boxes.
But a strong persuasive writer asks him or herself why they are doing everything that they are doing. Why are you starting your argument with that sentence? Why are you including that fact in your Statement of Facts? Why are you adopting an antagonistic tone? Why are you writing this brief in the first place? A strong persuasive writer relentlessly asks themselves why they are doing what they are doing, and constantly edits depending on the answer to that same question.
The overarching why? is further broken down further into three simple questions:
A strong persuasive writer has articulated for himself what he wants his reader to do or feel before he begins writing, understands his reader's biases, expectations, and predispositions, and creates and implements a strategy to lead that particular reader to that specific conclusion or emotion. It's not quite that simple, but you're a lot closer than you think...