Most college or scholarship essay prompts ask you to look back over the past few years to determine why you are an appropriate fit to be accepted. You should keep most of your essay in the context of the recent past, but you can talk about how experiences in your childhood shaped the last few years. If you had a life-altering experience when you were young that taught you the value of honesty, service or hard-work, this is a great thing to include in your essay. Those taking a look at these essays will appreciate that you looked so far back, and they'll understand you better as a person.
Like a good play or novel, your essay must stick to a specific theme instead of feeling patched together like a mismatched quilt. It is difficult to show all the different sides of yourself in an essay. You want to show that you are funny, intelligent, brave and interesting, but you should try to keep your essay unified by one theme. If the essay is about how a lack of money affected your upbringing, keep most of the essay related to finances. A random paragraph about your service record that doesn't mention money at all would be out of place and a departure from the theme.
Entice the people reading your essay by telling a compelling story. The introduction in this case will be like the first paragraph of a novel. Say for instance you had a near-death experience that shaped your high-school career. You can mention how you got into the experience but do not conclude it until later in the essay. You want the reader to be excited to find out how the story ended. Even if you do not have something as dramatic as this example, make your essay something that a reader wants to finish.
Several notable comedic essays have used the literary device of bathos to their advantage. Bathos is a literary device in which there is a giant build-up with a humorous, ironic twist at the end, typically in the form of a letdown. For example, "He came; he saw; he picked up his dry cleaning." According to The International Education Site, an application essay that led to a New York University applicant's admittance started with phrases like "I am a dynamic figure, often seen scaling walls and crushing ice" that ran throughout the entire essay. The essay details all of the fake and real achievements of this student before ending up with the sentence, "But I have not yet gone to college." A twist like this can be used to liven up an introduction or an entire essay.
Most importantly in an essay, you need to be yourself. No clever constraint or creative idea will flow if it isn't something you've come up with yourself. If you are funny, be funny; if you are serious, be serious. Show all of the fantastic parts of yourself with humility or humor (or both), and your essay can be a success.