Begin with a brainstorm. Use whatever format works best for you, such as lists, charts or webs, to get all your ideas out on paper. This will help you narrow down your topic and figure out what ideas need to support your overall goal of the essay. An essay's goal is generally summarized in your thesis statement. Write that one statement which tells the reader exactly what the point of your essay is and how you are going to make that point. Once you have your ideas down and your thesis written, create an outline to help you plan the structure of your essay. It's usually most effective to order your points from weakest to strongest so that your essay ends with a "bang." This outline will help you with the next step in the essay, drafting.
Take the outline you've created and let it be your guide as you write. Your essay should have an introduction, a body, and a conclusion. The introduction does just that, it introduces the reader to the topic and your essay. This only requires a few sentences. Let the last sentence be your thesis statement so that the reader knows what's to follow. Next comes the body, the substance of your essay. As you write the details of each paragraph, remember that everything should be relevant and connect back to the overall thesis statement which you stated in your introduction. Conclude by summarizing your body paragraphs and once again hitting on that thesis statement. Don't repeat yourself, but make sure that by the end of the essay you're still on the same track you started on.
Now it's time to go back and read what you've written. Once you've read through and made sure there are no blatant spelling or mechanical errors and that everything makes general sense, trim it down. Make sure your paragraphs and sentences are simple and to the point. Any unnecessary information you throw in will only distract the reader from your overall goal. Examine your transitions between paragraphs. Smooth transitions allow for easy reading and an overall cohesiveness that strengthens your essay. Check your verbs and replace any vague words like "do" or "have" with specific, more powerful words like "create" or "exemplify." Strong verbs will help you eliminate unnecessary adjectives and adverbs that may detract from the point of each sentence. Overall, make sure the ideas you showcase in each paragraph come with the necessary details and support that give your essay the credibility it needs. After you make these edits, read through the essay again. Make any necessary changes and keep rereading until you're completely satisfied with your hard work.