Some applicants may ramble on about themselves in a manner that may appear self-indulgent and not very appealing to the committee. Remember, this is an application essay, not an autobiography. Conversely, some applicants tend to say too little, perhaps hesitating to promote themselves too explicitly or not knowing what about themselves would be interesting to people whom they don't know. In such cases, perhaps focusing more on what you want to do than on what you have already done (let your record speak for itself) may help in getting beyond self-inhibition.
Personal essay is one of the richest, most vibrant and rage literary forms. As it gives you an opportunity to exceed the limits of the standard essay, to utilize conversational tone, dialogues, settings and characterizations. Before writing your work you should try to plunge into you inner world, get to know yourself from the inside and gain the understanding of the self. Writing your personal essay intends to vent your thoughts, ideas, interests to the others and lets you drive toward candor, self-disclosure, honesty with yourself. After such a revelation with yourself you'll be surprised by the quantity of positive sides you've got.