Study the questions being asked. Keep the individual school, department, and program in mind as you prepare to answer each question or point being sought. When designing your personal statement, avoid repeating what has been stated in other parts of the application. Focus on telling your personal story when you answer the questions. Look at yourself as a unique individual.
Most graduate schools attempt to diversify their students.
Answer questions with a focus on what makes you unique, fits into that particular program, and would be a broadening of the backgrounds of students within that program. Sample graduate essays can be viewed on the internet.