Oftentimes the hardest part of writing is getting started. I do believe that if you simply write, and write anything, you’ll at least have some ideas on paper. These you can then shape, refine, redraft, rework, into what you need it to be.
Read the opinion pieces below. Each are excellent examples of how a writer can develop a particular tone and contention, and maintain that through an interesting, well-informed, and persuasive piece. The Atticus Finch piece is brilliant in terms of showing you how you can link a contempory idea with those inspired by a text.
The sample responses that Mr Johnson has written shows how you can write a generic piece around an idea, and then shape it to fit a specific prompt.
Just keep thinking of ideas that are piquing your interest. Are you already leaning towards arguing/exploring a particular viewpoint?