A common mistake for students is to send the same essay to all schools; instead, you should tailor every essay to each distinct program to which you are applying. In order to do this, you must first research the individual programs to know what exactly the requirements, curricula, expectations and benefits are. This way you can address these distinctions in your essay, thereby showing the admissions panel that you are familiar with that particular program and have put in the work to cater your application to them. Topics you can research include professors, work-study programs, fieldwork options and relevant instructors and alumni.
The essay is the only part of a graduate school application that is open-ended. This means it is up to you to select how best to present yourself, your goals and the quality of your candidacy for each program. The University of California Berkeley suggests writing about what specifically you intend to focus your research on, and with whom you would like to work. The non-profit organization Idealist writes that you should discuss "what you want to study, and how you plan to use your education." By detailing your long-term career plans, you are showing the admission panel you are organized and focused on your goals. Your essay should explain how the program and your previous college experiences directly support your goals.
Many applicants have at some time faced a challenge which they have had to overcome to proceed toward their goals. If this is the case for you, write about these obstacles to show your perseverance and dedication. This aspect of a doctoral essay explains the purpose and motivation behind your academic and professional intentions. It also provides a critical opportunity to make you stand out among the other applicants. Be careful, however, not to get too caught up in telling the story of "what happened" -- instead, focus on what you learned and how that impacts who you are today.
Once you have finished your first daft, proofread the essay carefully to avoid grammatical mistakes. Your doctoral essay, as with the rest of your application, represents you as an applicant; therefore, it should be polished, professional and of high quality. When reviewing it, look out for clichés -- your paper should be original in both wording and content throughout. Also give the essay to others to review and provide feedback; in particular regarding parts that are unclear, need more development or are too general. After you have received feedback, revise the essay to create a second draft.