I agree with all that has been written in response to your question so far. I'd add one more thing, though it may or may not be helpful for YOU. Imagine, if you can, that you are NOT writing this essay to "get into college." Imagine instead that you are writing it for no reason other than that the subject matter means a great deal to you, perhaps even to the extent that what you have to say is a part of what makes you who you are. Better essays in general (in my opinion) are passionate as well as well put together.
One piece of advice suggested that you look up the college to which you are applying and identify how something they showcase is something that impresses and attracts you, and how you will both make use of that showcased quality and contribute to the campus. This is good advice, but may lead you into the "pick me" camp, unless what you discuss is both VERY specific and VERY special to the college in question.
I would advise that your essay needs to be honest. Write what is true, in the most basic sense, to you; what feels true in addition to what is factually true. I met some friends in college who had written very specifically about what it was at Brown (where I went) that attracted them specifically. But the things they wrote about were very VERY specific, and not generally broadcast to the universe at large. At least not at loud volume. They had discovered something others might have overlooked, and imagined themselves into a world with that something (or someone).
The "topic" of my essay sounds, even to me, like old hat: as if it would be boring, dull, and not particularly attention-getting. What did I write about? Being the only daughter among four children, and the youngest as well. However, I wrote it with great specificity and with what I hope was passion. My brothers were and are immensely important in my life, in virtually every way one can imagine. Each of my brothers is tremendously unique, and each in a different way contributed to who I was becoming.