In planning your paragraphs, you must give the Admissions Officer a glow so they will wish to continue the next section. To illustrate the structure, let's take a look at the typical personal statement organisation. The first paragraph will need to be an exciting and dynamic narrative to capture the reader's attention. The subsequent paragraphs should outline why you wish to study for your particular field followed by a compelling powerful final paragraph with strong action verbs to give your reader the final push to admit you.
It is important to put yourself in the shoes of the Admissions Officer: why would your personal statement be unique, how are you different from the other candidates? Primarily you need to decide how you will divide your personal statement into digestible chucks. The most obvious way is to divide into paragraphs of 100 words. If you aim for between 500 and 600 words at most, it will help your admission officer when they have to read thousands of personal statements to find the perfect student.