I had done Masters in English Literature before clearing the CSS Exams and I would advise you not to use headings in the essay paper.When you start your essay be like an artist who is sketching a given scenario on the canvas. Try to be illustrative.In the middle of the essay sound like an advocate, giving reasons, logic,facts, figures etc to support your point of view. At the end be like a judge who sums up the whole argument, sounding wise, judicious, truthful etc.