Here's the most common mistake I encounter among applicants about application essays (aka "personal essay"), whether for undergrad or grad school:
Unless you are applying for an MFA in writing, you are not being evaluated for beautiful writing skill. Really. It's nice, but it's not necessary.
Instead, what separates the great essays from the meh essays are three things:
(1) Writing clearly
(2) Knowing what you want to say
(3) Protecting your voice from well-meaning meddlers
It's important not to write your essay by committee. If you have too many people weighing in, and you try to make all those people happy, your essay will turn into a dog's breakfast and you will have stripped it of the one thing that makes it interesting to read: your voice.
Why does your voice matter so much? Most of all, because admissions officers are trying to get to know you. The "you" beyond the numbers and the grades.
Voice also matters because you're not writing an English paper. Take that five-paragraph structure and drive a stake into it until it's dead. 🔪 You don't need intros, you don't need conclusions. You're telling a story.
Your essay is also signaling that your writing skill is good enough for the program you want to join. Those baselines can vary depending on the level and the program, but basic grammar and spelling matter. Basic proofreading matters.
Basic writing skill means you have to be able to say what you want to say within the word limit. Your writing has to be easy to follow in a very quick read. And avoid those adjective and adverb pile ups. You don't get points for those. Less = more.
Focus on what's important. All that time you spend worrying about whether you should use this verb versus that other one when they're both perfectly fine for these purposes... that's wasted time because that's not how or why they're evaluating your essay.
It won't make the slightest difference to the outcome if you use the long dash or the short one, if you say "effect" vs. "impact." I've seen applicants AGONIZE over these kinds of things.
Go back to these fundamentals and spend your energy on the things that have the power to affect the outcome:
Clarity.
Story.
Voice.
☕️
[Necessary caveat for some PhD programs: Those essays are typically expected to take the form of a research proposal. That's not a personal essay. Totally different beast.]
[Another necessary caveat: This advice is mainly for US schools or those that follow the US holistic admissions model. The rest of the world does things a bit differently, e.g. UCAS essays.]