Sell yourself in a way that shows you are amazing without sounding arrogant. Her trick was saying how awesome her accomplishments were while still sounding like a great team mate/classmate.
Tell your story in the first person. For example, she brought up her family's religion and heritage and told the story in a “this is what matters to me” sort of way.
Keep the readers interested, show some personalities. In one school she applied to, she used a metaphor through the entire first essay to explain her career goals, and a student reader described the essay as “endearing” at the admin weekend.
Don't focus on what they want to hear. She wrote on common topics - friends and family – with an emphasis on the why.
Write your essay as if you're publishing it. In other words, spend hours upon hours drafting and re-drafting till you love what turns out.