Writing a Blue Book Examination is the academic equivalent of going to war, well, anyway, at least defending something worthwhile. In general be specific. A good essay uses carefully selected examples. Like a good poem or a good piece of science or a good historical argument memorable essays make a general claim supported by specific examples. The general and abstract are grounded in the particular and concrete.
Time is short.
Because time is short your essay should show economy of expression. Make it lean and to the point. Truth is simple. Your reader can usually distinguish pepper corns from mouse droppings. Keep fertilizer to a minimum.