WS: Write an abstract, forefront conceptual questions of broad interest to people working with/in a methodological approach or theoretical area, clear structure.
SOP: Multiple reads from multiple people, especially outside of thematic area, Hook them in, Ask Good Questions, Demonstrate broad (conceptual) familiarity with work of POIs, Frame around trajectory of research, demonstrate broad familiarity with "questions of the moment" in your thematic area. Affect-wise, aim to sound like a young early-career professional as opposed to a student (e.g., ditch subjunctive phrasing, don't apologize more than you have to, explain things concisely, and so on).
LORs: Send a complete draft of your SOP to your recommenders relatively early, along with a document of school-specific paragraphs and a list of POIs at each program. Send near-final draft at least three weeks before the deadline. Send your recommenders abstracts of your writing samples, especially if you're writing them mostly from scratch.
Preparation: Reading over my materials again, I think what made the biggest difference for me is making an effort to read the works of other people less in terms of shared objects of study, and more in terms of what methods and theories undergird their close readings. I'm split on whether reading other WS/SOP would have been helpful, or not. Thinking maps can be very helpful. Long walks are good.