The bolding is mine, to emphasize topics I've seen debated frequently on TLS.
Here are some personal statement don’ts.
Don’t go over your whole work history or resume in your personal statement. If you want to elaborate on something particular on your resume that is fine, but we already have your resume and we do not need it in again written in prose.
Don’t use personal essay space to write about why your grades are low in your freshman year, why your LSAT isn’t an indicator of your potential, or why you switched schools three times. You should use an addendum to explain these things and save your personal essay for telling us about who you are.
Don’t send an essay to University X that says how excited you are about the possibility of attending University Y. Again, proofread.
Don’t write about how interesting the health law program is when that school does not have many health law offerings. In that same vein, don’t say you’re interested in health law (if you aren’t) just because a school has a great health law program and you think that’s what they want to hear.
Don’t start off your essay with a famous quote if you can help it. Admissions committees have all read numerous quotes by Thomas Jefferson, Abraham Lincoln, Martin Luther King, Jr., Aristotle, Thomas Wolfe, John F. Kennedy, Robert Kennedy, Margaret Thatcher, William Shakespeare, Winston Churchill, Barbara Bush, H.W. Beecher, etc. Starting your essay this way is not original.
Don’t try to write like a lawyer. Some people will use a lot of legalese or espouse what they know about the law. Your professors will teach you how to write for the legal field once you are in law school. Furthermore, if you attempt to show us what you know about the law, you risk really showing us what you don’t know.
Along the same lines, don’t tell us what the law does or will do. We know that already. This type of essay does not tell us about YOU, which is something we don’t know and are hoping to learn more about.
Hopefully, this will help guide you in writing a stellar essay and avoid some of the pitfalls that applicants encounter with this piece of the application. This could be the most difficult and also fun part of the application process - try to attack it in a positive way!