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.
oMake sure you haven't constantly used the same word in the same paragraph. This can be very irritating to the admissions officer and it only needs a little more thought to re_word or, very often, it can be omitted without affecting the sense. A thesaurus is useful for finding alternative words.