Using quotes is fine, but make sure you are not trying to make the quote do work for you. For example, don't use a quote to explain or illustrate something you could simply explain yourself. Furthermore, I worry that applicants use quotes in their essays to give more credibility to what they are talking about. You don't need to add credibility to your essays. They are your personal opinion, which makes them absolutely right (as long as they are the truth).
Like GKumar, I am not a big fan of putting quotes at the beginning of essays. I only let my clients keep those in if it is a really outstanding quote that sets the tone for the entire essay. Otherwise, it just comes off as, well, corny.
Good luck!
Kaneisha
Harvard Business School MBA 2010, Harvard Kennedy School MPA 2010
Founder, The Art of Applying
Admissions Consulting for MBA, MPP, Joint Degrees, and Fellowships
https://theartofapplying.com
Want free advice that actually works? Sign up for my weekly MBA, MPP, and JD newsletter here:
https://theartofapplying.com/newsletter/
My clients have earned over $3.1 million in fellowships from Harvard and other top MBA, MPP, and JD programs since 2010.