Pick an interesting topic
This is one of the most critical aspects of your scholarship essay. There are some scholarships where they have a predefined topic, however you will want to tailor these topics to address one of the following issues. I have found that focusing on these issues will greatly increase your chances in winning the scholarship.
1. Focus on a major accomplishment
You're going to want to impress the reader of the essay, so when writing about a major accomplishment, you want them to say, "wow, this person really does deserve this". Keep in mind that an accomplishment that YOU think may be major, may not be major to the eyes of the reader. For example, writing about how you were able to stuff 20 marshmallows in your mouth is probably something that you can forget (until college starts, then you can tell or demonstrate to all your college buddes).
2. Focus on an event where you took action
Readers of scholarship essays LOVE iniative. This means that you saw a need and you actively pursued to fill that need. Some examples of this are being the ASB President, starting up a club, helping out less fortunate kids, etc. People who do these types of activities are most likely going to succeed in life, and the readers know this, so use it to your advantage.
3. Focus on an obstacle you overcame
Here, I would like you to you focus on adversity that has occurred in your life and how your managed to overcome in. Some examples would be the loss of a parent, living in a world with divorced parents, having a disability. These are the types of situation where when you tell somebody, they give you this puppy dog face and say, "I'm sorry". When you write about these events, it is imperitive that the focus is on how you overcame these obstacles and to stay positive. When a reader finishers your essays, you will want them to say, "Wow, this person has gone through a lot, this person deserves this scholarship".
Fully research your topic
I know that when you start to apply for scholarships, you will realize that you will need to write a ton of essays! You will feel that you can skimp on all the essays and focus on quantity, and not quality, but SHOULD not be the case. This is an automatic path to rejection.
Give yourself 2 weeks time for research and the writing of the essay for each essay you do. This will allow you to fully think out the topic and have enough time for feedback and editing.
Remember to focus on QUALITY, not QUANTITY.
Write for your audience
When I talked about some of the topics you should write about, I said that when the reader is done with your essays, the reader should say, "wow, this person really does deserve this essay". You will need to do this when you write your essay. Put yourself in a reader's shoes and ask yourself if you really do deserve this essay. Keep in mind that the reader may have to read tens to hundreds of essays of varying quality, and it is his/her job to pick just ONE. Do you truly think yours will be the one chosen?
In addition, you can tailor the essays to the foundation that provides the scholarship. Say, you want to apply to your parent's company scholarship. You could write a little bit on how your parent's company has affected your life in a positive manner.
Make your essay different from the other essays they get
This comes back to the fact that the reader has to look at tons of essays and needs to choose one. One way to do this is to show, not tell, your reader about your topic. Focus on specifics so that you can avoid vagueness and you'll be able to make an overall stronger impression.
Another way to do this is to take a totally different creative approach to writing an essay. I can't find the link to it right now, but I remember someone won with an essays that went like this.
"I have never parachuted from a plane. I have never taken a canal ride in Venice. I have never seen the light as feathers snow in Russia. I have never won a scholarship."
As you can see, this is a totally different way to write an essay. So be creative, and try something different. Your readers will notice it.
Get someone to proofread your essay and keep editing!
Too many students treat their scholarship essay writing like a regular essay for class. Students will write their essays a couple days (or on the day) it is due and proofread it themselves 1 or 2 times. They don't show it to their parents, or other teachers. You must remember that this essay will generate between $100-$100,000, so treat it like that! Show it to your parent and at least 1 teacher before submitting it. This will greatly increase your chances in winning the scholarship