Don't Stand Out For the Wrong Reasons
I assist with admissions for a graduate program at a large University (40,000+ student population). Our program sees over 400 applications per year, first an online application, and then we do in-person interviews. You're probably doing most things right when applying, spell checking your submissions, make sure your references are strong, meet all the requirements, etc..
Things you DON'T want to do - make yourself stand out in a negative way. Any applicant who doesn't submit docs on time, whose interactions with staff are rude/negative/pushy (including reception) - we note and keep track of all of that and you will not be getting an interview, despite what your GPA may be. If you waited until two weeks before the submission deadline to ask a referee to send a letter and they didn't get around to it? Don't call and ask for additional time, there's a deadline and it was your responsibility to meet it. Didn't like the answer you got to an emailed question? Don't come in after seeing our note that we don't do in-person advising, and try and pressure staff into giving you a different answer. Don't, for the love of god, have your parent call or come in on your behalf. There are privacy laws for a reason and we don't want a student who can't ask their own questions. Unsure if your documents reached us? Don't call or email to ask about them; read the instructions we listed that stated to check your online application as all updates will be made there and that we won't take call to confirm. Don't ask to speak to the Department Head or an Admissions Committee member because you have a 'unique' situation. We note everything. We receive enough applications from students who exceed all of our minimum requirements that we can afford to be extremely picky.
The people who do stand out are the ones who did everything that was asked of them; submitted all documents on time, met and completed all requirements, didn't come in when we said not to, didn't make a fuss, were passionate, enthusiastic and had a positive interaction to everyone they interact with.
Don't just be a resume filler. One year in the environmental club, one year in the history club, one year in the robotics club, etc. shows you're just trying to con your way in. Find something you really enjoy and stay devoted to it. Show you're willing to put in work for something you care about, not just go through the motions.
Part-time jobs. In this day and age a lot of kids go to college never having held a job. If you did have a part-time job and can get a letter of recommendation from your boss (responsible, hard working, gets along well with others, reliable, honest), it goes a LONG way.
Copy & Paste is Not Your Friend
You'd be surprised how often people use a copy and pasted response to questions, or even their entire admission letter. You can have the best application ever seen, but your chances drop instantly if your admission letter for University X still says "for these reasons and so many more, I believe University Y is the perfect fit for me."
Ok, so go to University Y. Application rejected.
Spell Check Your Grammar
A surprisingly large number of essays include obvious typos and grammar issues. Use spell check, read your essay aloud, and have a few other people read it to check for errors. I want to know that you're taking this application seriously.
Give me a sense of who you are. What makes you different than your peers? What would make you an interesting member of my college's community? I want to see some personality. It's not strictly necessary, but it helps me understand you and why you're a good candidate compared to the other couple of dozen applicants I'm reviewing today.
Own Your Mistakes
If there are problematic areas in your application (for example, some bad grades or weak extracurricular activities), give me some context. I want to understand why you're still a good candidate. I really want to admit you. As a college, we need the tuition and financial aid money you can provide, and we can't get that unless you're admitted and enroll. So explain those bad grades or other problems that might make me think you would struggle in college. Be careful not to shrug off responsibility for your own actions, though. Ideally, I want to see you take ownership of your struggles and that you've learned from them, with evidence that you've improved.
No Generic Essays
In your essay make sure to tailor the reasoning to each school. Each one is different. Some are research focused and some are mission based. Make sure your reasoning for attending the school is laid out. Try to talk as little as possible about other people. I've read essays that talk about all the great things someone's parent did but gloss over what the applicant does. Then on the other side there is the applicant that looks full of themselves. I'm not saying don't brag, in fact do it like your looking for a job, but make sure you aren't over zealous and are realistic with your goals. (This next part applies to the 90% of schools that aren't Ivy League or STEM heavy) I see applicants who say they are going to change the world. Odds are you won't, and what then. Will you drop out when you see you can't cure cancer after 2 years of undergrad or med school. What is a realistic plan that will work if you stick to it. Thinking you will solve a problem on your own when there are literally tens of thousands of people working on the same issue is unrealistic and will sometime cause us to pass on an app. If your applying to MIT or Berkeley and you make these claims you better already have 2 years of research under your belt that is showing promising results.
I've worked in admissions to an undergrad honors program.
Humor is fine, but morbid humor is generally hit or miss.
I'm scanning your recommendations for actual examples of your awesomeness, as everything is generally going to be boilerplate "best ever!" so if your recommendations have a particulary example "he wrote an essay that made me cry"/"he was the fastest at (whatever)"/"he always stayed to help after" it's helpful. Remind your recommenders of these moments before.
Also on recs: I've read some REAL BAD ONES. Every once and awhile there is a person who asked the wrong teacher. If a teacher seems reluctant DO NOT TAKE THEIR REC ASK SOMEONE ELSE.
I'm expecting you to have reasonably good grades, so I'm probably scanning your grades for "mistake" grades that you need to explain elsewhere. Why did you get that D? What classes are your weaker classes? if you got below a C- in a class, you probably need to explain that to me.
Let someone read your essays for cringe. Please don't write an essay about how a 2 day volunteer trip changed your life unless you actually started volunteering everywhere else/created an NGO for that cause after. I'd rather hear more about your life and activities/hobbies as a whole. Please, if you're going to exaggerate, don't make it something which is basically a lie.
Submit your application online. I work in admissions and getting paper applications is not only annoying but it slows down the whole process. For one the amount of spelling errors is alarming and we end up having to call people to see how to correctly spell their first name. Second as much as it sucks, sometimes paper apps get lost. Get lost in the mail, doesn't get filed properly. Things just move a lot quicker online.
Know What You're Talking About
I work in the admissions office of my school. Improper emails, misspellings, terrible handwriting all make us critical of whatever you're going to say next. The thing that agitated me the most however , and probably the people that make the actual decisions, is your level of research on your career. "Elementary school math teacher" is not what you put in the blank for major; "Education" is a major. It's astounding how many potential students don't do research before applying. Last week we had an applicant that wanted to go to the NFL.... we don't have a football team.
People often forget to answer the most important question: what do you want to study, and why? You'd be surprised how many personal statements I read that are full of fantastic achievements etc, but none of that matters if I can't tell what you're applying for!
The number one thing that kids like to just wimp out on is recommendations. They saved so many asses when it came to kids being accepted. For example:
Kid 1 - has a 2.6 GPA, 21 ACT, has a great recommendation from a teacher who explains their struggles or their constant growth, anything flattering that isn't too over the top.
Kid 2 - has a 2.9 GPA, 23 ACT, has a generic recommendation sheet from a counselor, usually just a blank sheet with someone basic info, only a simple recommendation signature from a counselor.
You would not believe how many times the school would pick kid 1. Having a personal educator saved them and got them admitted over someone slightly better in terms of academics. Character is looked at a lot by universities.
The thing people do is share things they absolutely should not be sharing. Let me tell you about how my friends and I do meth every day in gym class... Even if I wanted to give you the scholarship, I can't now, because "Meth addict gets full ride to X school by bragging about being a meth addict" is bad press for the school. Just don't write about your criminal activity, okay? The vast majority of those are things like "I think drugs should be legal because I smoke all the time." But there are a few like "I killed a kid and no one knows." WHAT. THE. FUCK? I had to call the cops on that guy, which was definitely not how I wanted to spend my afternoon.
The last bit of overshare is people talking about how they aren't inspired and don't try hard at their school. Again, you're an idiot. Why would you tell a school that you don't want to be in school? Why would you tell a school that you don't like school? Why would you tell a school that you think school is stupid? You are the stupid one in this scenario.
Many universities (UChicago, Penn, Michigan, Columbia, Brown, Yale, Stanford, Cornell, Carnegie Mellon, etc.) ask "Why our college?" or a combo between "Why our college?" and "Why your major?" BE SPECIFIC. I cannot tell you how many essays I read for UChicago that were like "When I visited your campus, it felt magical. I was surrounded by students who were so driven yet friendly. As I explored your biology major, I found great classes like organic chemistry and intro to biology, and I just knew that such a prestigious university would prepare me for medical school." BLAH BLAH BLAH---all this could apply to any school! Be extremely, extremely specific. Research the school extensively. Find classes that the university offers that you haven't seen at any other school (o-chem doesn't cut it). Mention the curriculum (Core at UChicago or Columbia, Open Curriculum at Brown, for example), and don't just say you like it---really dig into WHY that curriculum exists from a fundamental educational level and what sort of catalyst it will be for your own thinking. Search the school's online newspaper for some cool programs that other prospective students might not know about, talk to current students/alumni (if possible) and incorporate things that you learned. Ask them what underlying qualities the student body possesses (for UChicago, it's a thirst for knowledge, and at Georgetown, it might be some Jesuit value), and evidence your possession of those very same characteristics in your essay. Mention specific professors under whom you wish to study/research, and connect their classes/research back to your own intellectual interests. Better yet, email the professor, have an awesome conversation with them, and incorporate some element of that conversation in your essay. Bottom line: If the essay can be copied and pasted to fit any other university, be more specific.