Avoid Cliches. There are a few standard reasons why people become doctors, and so it is very easy to fall into cliched expressions and ideas. Though it's fine to express a commonly_held notion, try to find a personal way to express it. For example, rather than write "I want to be a doctor because I want to help people," discuss the ways that you have shown your generosity and kindheartedness in the past; bring specific examples__such as your volunteer experiences__so as to avoid a direct (and possibly cliched) declaration of your point. Sometimes cliches are unavoidable; just make sure your essay isn't full of them.
One approach is to begin with an interesting statement, then follow it with a brief overview of your main theme. e creative with your introductory paragraph. Another approach to make it unique is to use personal information that distinguishes you from the rest and makes the essay stand out from others. Another approach is to use a fact or a literary concept, which is relevant to your theme. Paraphrase it or use a direct quote, and add in whatever point you are trying to make. As much as you would like to present a good introduction, do not fall into the trap of making hasty generalizations, sweeping statements, and/or other pronunciations. Keep the tone light and personal. After all, you are telling your own story.