With the focus sentence clearly in mind, take some time to “play” with your topic: bend it, see it from various points of view, visualize details, narrow and expand it. As you work your topic over, jot down details and ideas that might work. Don’t worry at this time about arranging them; allow them to jump onto the paper without censorship. Once you have explored your topic, go through your list and prune it. Some points may be too trivial, some may require too much explanation, and others may work to fog your overall purpose. Which points are your strongest? Does anything need to be added? Which are the most relevant and interesting? Take those ideas and details that survive this pruning process and put them in the best possible arrangement.
Since your essay must communicate efficiently and effectively, your ideas must flow logically, reflecting clear and reasonable relationships. A thoughtfully designed blueprint is required before you write. Take the time to develop an outline. More than likely you will not need an extensive formal outline. But a sketch outline is indispensable. When you sketch out your essay before you write, it will sound more organized, systematic, and purposeful. Acceptable prose becomes readable when it follows a well conceived plan.