I always advise my students not to be daunted by word limits when brainstorming ideas/stories for their essays. At that stage, your goal should be to put down on paper all of your ideas related to the essay prompt without fretting if the essay exceeds 100 or 200 words over the word limit. Go on a soul searching journey, reflect on your experiences/stories and choose the examples that touch upon a variety of key themes at once. Once you have made sure that you have chosen your best story and have narrated it in an organized and engaging manner, you should identify areas that you think are not adding significant value to the story. Then go ahead and begin eliminating those details without compromising on the essential components of the story. Also, omit repetitive content (if any), and replace big phrases by shorter ones. Brevity is the key here. If you choose your words wisely, you can accomplish this feat.