• Pick a topic that you know about and care about.  Something that reflects well on you and demonstrates the confidence you have in yourself.
• Winning essays include personal anecdotes, so be sure your topic is one with which you have hands-on experience.  Also be sure it's something that can be easily covered in the allotted number of words.
• Brainstorm possible topics.  Make a list of five to ten.  Wait a day and start a new list.  Wait another day and start a third list.  Eliminate topics not on all three.
• Ask your family and friends topics they would suggest and why.  Discuss your list with them.
• Settle on a tentative topic and a runner-up.  Begin writing on your tentative topic.  If you find yourself struggling switch to your runner-up.

• Develop a central idea for your topic.  Encapsulate the central idea in a single "master sentence".
• Jot down as many aspects of the idea as you can think of.  Do it rapidly.  Don't worry about grammar, spelling or the order you write things in.
• Group the aspects under a few main headings or subtopics.  Let the bad ones go.
• Logically arrange your subtopics.
• Logically arrange the aspects grouped under each subtopic.
• Turn each aspect into a sentence or two, and each group of aspects into a paragraph.

Your work should be unified
A paragraph is unified when it only contains sentences which contribute to understanding the subtopic.  An essay is unified when it only contains paragraphs which contribute to understanding the central idea.  As a discipline, compare each sentence to your master sentence.  Ask yourself, "Is this getting me off on a tangent?"

Your work should flow
There is a natural logic to organizing an essay.  If you're telling a story, things should build toward a climax.  If you're writing a history, things should unfold chronologically.  

Your work should start energetically
Grab the reader's attention with something dramatic.  Pose a profound question or paint a picture of an interesting location or event.

Your work should be tight
Never use more words than necessary.  Never use bigger words than necessary.  Don't repeat yourself.  Vary the words you use.

Your work should be thoroughly critiqued
Do yourself a favor-- the more people who review your essay the better. 

• Applying to college- try your high school counselor and teachers
• Applying to grad school-  your academic advisor and willing professors
• Applying to law school- have a lawyer you know read it
• Applying to medical school- a doctor
• Generally speaking any one whose opinion you respect can help you by reading your essay and giving you feedback

Your work should be revised as needed
Don't be afraid to improve your essay based on the insights of others.  Even if you defy the laws of nature and create a perfect essay in one sitting, you should wait a couple of days and reread it.  Chances are you will find things that you yourself want to change.

Your work should be "neat and tidy"
It is critical your essay be grammatically correct and free of spelling errors and typos. Any punctuation lapses or misspelled words will jump out on the page and cost you points.