The most humiliating moments occur when applicants emphasize that they possess certain abilities or skills and then get caught red-handed committing sins that contradict their assertions. If you tell an employer that you have extreme attention to detail and you accidentally say that you held a job from 1999 to 2015, you will look ridiculous and your credibility will be damaged from then on. It is really that simple, which is why it is so important to draft and review your resume and cover letter as though your life depends on them. It does...well, maybe just your professional life.
This leads me to the first pet peeve of many employers. You know what? I am actually going to be bold and say all employers. There is no tolerance for misspellings, typos, and poor grammar in resumes and cover letters—unless you are lucky enough to have your potential employer overlook such mistakes, but I would not bet on that. This is one of those things that does not give you an extra advantage but, rather, is expected. Make sure that you do not put all of your faith into your word processing program's spell checker, as it may not catch unfamiliar words and misuses of words. For example, if you type in "manger," meaning to type "manager," the spell checker will leave it because "manger" is the correct spelling of another word.
It is invaluable for you to proofread your resume over and over, until you are sick of looking at it, and then make someone else look at it at least once. Even after making adjustments, make sure that you set it aside for awhile and then look at it another couple of times before sending it out. It sounds obsessive, but you have to be obsessive in order to ensure that all mistakes have been caught. One mistake can kill the brilliance of the entire document. Why do you think many companies hire proofreaders? People get paid to be those extra sets of eyes catching spelling and grammar errors. Do not let a simple mistake hold you back from landing your dream job.
Along with meticulously proofreading, always research and find the correct spelling and punctuation for every company and personal name you mention. Simply guessing is not good enough. Also, if the employer's name is unisex and you plan on addressing him or her as Mr. or Ms., do everything in your power (aside from harassing the employer's office) to find out the person's gender. He or she will surely be peeved if you get it wrong because, unlike other cover letter and resume mishaps, this one is personal.
Surprisingly, many employers complain about applicants leaving misspelled or missing contact information. Imagine this beautiful scene: an employer looks at your resume, a pleasantly impressed smile crosses his face, he refers to your cover letter, another smile crosses his face, he is sold...and then he looks back at your resume for your phone number to call you in for an interview, but you seem to have neglected to include that information. Okay, the employer is annoyed, but he likes you, so he proceeds to locate your email address, which, thank God, is there. He writes you an email asking if you are interested in meeting next Monday at 10:00 a.m., even going so far as to compliment your excellent writing ability. When he returns to his inbox, he sees the dreaded email subject heading that so many employers come across when attempting to contact applicants: "Delivery Status Notification (Failure)." If he has not already stepped into the hall to scream in frustration, he will probably immediately toss out your resume and cover letter. At this point, you have not only wasted his time, but now he has another useless piece of email filling his inbox, and he has no way of contacting you—even if he still wants to, just to scream at you. This sort of event might be called a "deal breaker." Tsk, tsk. So, in conclusion, make sure that you include contact information, and make sure that it is correct. Need I say more?
Employers are also annoyed when they look at resumes that are cluttered and lacking in organization. Always choose a standard, easy-to-read, 10- to 12-point font and ample-sized margins. If you have many years of experience, then you may have to break down and make your resume two pages long. Do not try to squeeze everything onto one page if doing so will sacrifice the quality of the document. If you are only a few years into your career, you should be able to compose a decent one-page resume. Sometimes, you may need to omit information that is not necessary in order to avoid squeezing in and compacting words.
Also, remember that a resume is not a cover letter, meaning that an employer does not want to see a continuous stream of words, line after line, as he or she reads your resume. Break up sections with bullets, dashes, spaces, and lines, creating an eye-pleasing arrangement of words. Using a slightly different font for your headings to differentiate them from the rest of the text can add some style and clarity, as well.
Above all, read over your cover letter and resume repeatedly, reflecting on what a potential employer would want to see. It is the attention to those small details that will get a stellar job candidate noticed in a sea of mediocrity.