Decide on your essay subject. Many colleges will offer a choice of open-ended questions to answer with the essay. Carefully look over each question and decide which is best to answer, since one may be more suited to you than others. Choose the one which best highlights your strengths. If you are allowed to pick your own topic, think about what you are passionate about or what sort of life philosophy you have.
Write down a few notes pertaining to your chosen topic. Brainstorm through the topic to come up with ideas. Make notes about how you want to present the information to the reader.
Write a first draft of the essay. While writing, try to give the reader a sense of who you are and what values you hold. The essay should come across as written introduction. The reader needs to see that you have taken an original approach to the topic. Write clearly and vividly to draw the reader into the topic at hand. Spend time on the introduction and have a clear thesis statement. Write supporting paragraphs which stem from your introduction. Give the essay a proper conclusion.
Proofread the essay. Look for misspellings and incorrect paragraph or sentence structures. Take out any "big" words you added with the help of thesaurus. Many students think this impresses colleges. If you have a big vocabulary, it will naturally show. Mark the draft when you find sections which don't flow naturally or that you want to change.
Ask your family and friends to read the draft. Many times a fresh set of eyes can offer suggestions for improvements.
Rewrite the essay for your second draft. A full rewrite will not only give the essay a fresh feel, it will also help you change or clarify points for a better overall read.
Continue the process of rewriting, making notes, getting feedback and proofreading.