Don't touch your key board...put that pen down and review this list first.

Don’t write what you think a committee wants to hear. The more you try to craft something for them, the more it will fall flat. You never know who will be reading your application or what they are seeking. They just want to know what makes you tick. There are very few topics a reader has not seen, so just be yourself!

Don’t write in a style that is not yours. The essay should reflect your personality. It is disappointing to see an essay written in a severe and formal style from someone who is clearly known for a sense of humor. On the flip side, an essay should not be an attempt to entertain the reader, but if you are more casual, you can be a bit relaxed (with proper grammar and language). But please do not attempt humor if you are a serious person; it is simply painful to read.

 
Don’t have someone else write it. A committee knows when something sounds “wrong” in an essay because they read thousands of essays a year. There are also testing data and grades for English in the application, so if the writing is very different from those indicators, a reader will know something is fishy. Do not make this mistake and lose your chance of admission.

 
Don’t vastly exceed page limits or word limits. A well-written essay can say everything you want or need in the limits of the essay. If you cannot seem to write close to those limits, you are likely going off-topic or talking about unnecessary things. An essay should be about a small, focused thing—not a broad discussion—and this should be kept to about a page or two.

 
Don’t play with margins and fonts to squeeze in more. What you are doing is obvious, and if you happen to be the 30th application of the day for the reader and your font is small, it is not fun.