In order for your essay to be effective, you must have a clear purpose in writing it. Only then will your message be clear. Resist the urge to simplify you message in generalized ideas about why you have to write the GRE essay in the first place.
Assume that you are asked to write an essay for the GRE test about the impact that drunk driving has on individuals and society as a whole. You have decided to write about the time a close friend was involved in a car accident after drinking and driving. A poor statement of purpose would be the following:
I am going to write about when my friend was hurt drinking and driving because it was an important event for me. I will be writing about this event is to say that it was important in my life and changed the way I thought about drinking and driving. The purpose of this essay is to say that this was an influential event in my life.
While this purpose identifies a potentially very powerful life event, it does not say why exactly this experience was important. Furthermore, it is simply a personal account of an event. Instead, you'd want to also discuss the broader impact of drunk driving. The last sentence of the statement of purpose illustrates a very common mistake. It makes the circular argument that the event is important because it was chosen for the essay. Your readers will not assume that because you chose this event, it is necessarily important. It is up to you to illustrate why the event is important not simply that it must be because you are writing about it.
A better statement of purpose for the same example would be:
I am going to write about when my friend was hurt drinking and driving because it was an event in my life that taught me the importance of responsibility. Also, drunk driving places an undue burden on law enforcement officials, and thus detracts from the use of tax-payer money on other social services that might better benefit a community. The purpose of the essay is to convince my audience that I learned from this event and that it was an experience that I will carry with me throughout my life. I want the audience to know that this experience changed the way I view my friends, my social life, and the trust that my parents have in me.
This statement of purpose is much more successful because it is more specific, and it also incorporates aspects of a broader message that is indicative of the type of higher reasoning that you want to demonstrate on the GRE essay. Instead of just assuming that the event was significant, it begins to examine why it was significant. Here we begin to see that the focus of the essay will be on a life lesson that taught the value of responsibility, and also that drunk driving has a negative impact on the ability of a community to effectively use tax payer funds.
Having this level of specificity will be extremely important when it comes to organizing the essay. It is much easier to create an outline of an essay that examines how responsibility is learned than it is to outline an essay without an overall message (one that might suggest a story is important simply because it is being told).
Here are important questions to ask yourself when you are thinking about the purpose of your GRE essay:
The last question is the most important one. Personal stories and examples are helpful but only if they are used to illustrate a larger idea or issue. A good essay does more than just tell a story.