Avoid undue repetition. Don't make the personal statement a narrative description of all of your activities previously identified in Items 2-4. Highlight the most important. Answer the questions concretely and specifically. Except for Item 15, you should have precise, well-focused answers responsive to the Item.
Depth is better than breadth.
Engage the reader quickly. If you cite statistics or political developments or provocative writings, they should be up to date. Be careful about examples from high school days or early childhood. Understand the goal of the personal statement. The main goal of the written material is to get an invitation to the interview and to present some lines of questioning.