Since there are so many different kinds of successful essays, no guide can tell you specifically what material to include. You are the master of the details in your experience; you are the master of ceremonies as you present your words to the reader. Even so, the usual guidelines about essay writing apply: see "One Point Per Paragraph," "Don't Forget the Point," "What Counts As Evidence," "Transitions," and so on under Academic Essays.
Even so, an admission essay is often much shorter than an academic essay. Try cutting every paragraph by half, just as in the introduction. Make sure you know what each paragraph is accomplishing, and be able to explain how each sentence contributes to the goals of the paragraph. For example, a lot of description of the scene is great when the point is to evoke the scene, but very questionable when the point is to do something else.
