Some applicants may ramble on about themselves in a manner that may appear self-indulgent and not very appealing to the committee. Remember, this is an application essay, not an autobiography. Conversely, some applicants tend to say too little, perhaps hesitating to promote themselves too explicitly or not knowing what about themselves would be interesting to people whom they don't know. In such cases, perhaps focusing more on what you want to do than on what you have already done (let your record speak for itself) may help in getting beyond self-inhibition.
The conclusion gives the overall verdict of the argument. You can also restate the ideas that you have discussed in the body paragraphs so as to make your point valid. The conclusion should also aim at motivating the reader to do research in the future. The conclusion is related to the argumentative introduction as the topic as well as the thesis statement is restated in a more convincing manner. The conclusion also gives you a platform of illustrating your decision concerning the argument in the article and why you have settled on that particular decision. Try not to introduce new ideas as they will give the readers an ideology that the article is not comprehensive enough.