According to Resume.io research, 49% of hiring managers say attaching a cover letter can improve a candidate's chances of getting the job (Resume.io Cover Letter Statistics, 2025).

The guidance below covers every do, every don't, and the most common mistakes that cost otherwise strong applicants an interview.

What are the most important dos for a cover letter?

The foundation of any effective cover letter is simple: make it easy for the hiring manager to see why you are the right person for this specific role.

Every do on this list serves that purpose.

Tailor every letter to the role: Read the job description carefully and reflect the employer's language and priorities back to them. A letter that could have been sent anywhere will be read as one.
Open with what you offer: Your first paragraph should connect your strongest relevant achievement to the employer's most immediate need. Do not open with "My name is..." or a statement about how you found the listing.
Highlight achievements, not duties: Use the cover letter to show what you accomplished, not just what your job involved. A specific number, a percentage, a result, a timeframe, is always more convincing than a general description.
Research the company first: The content of your letter should reflect a genuine understanding of where the company is heading. Hiring managers can tell immediately when a candidate has done the work and when they have not.
Share content that is not on your resume: Your resume and cover letter should work as a pair, not as repetitions of each other. Use the letter to expand on context, motivations, or stories that do not fit neatly into bullet points.
Use relevant keywords naturally: Over 97% of large employers use applicant tracking systems to screen applications before a human reads them (Jobscan, 2024). Identify the key terms in the job description and work them into your letter without forcing them. The writing still needs to feel like writing.
Express genuine interest in the role: Be direct about why this particular job appeals to you and why you believe you would succeed in it. A hiring manager reading a flat, indifferent letter will not feel motivated to invite you in.
End with a clear call to action: Close by expressing that you welcome the opportunity to discuss your application. A confident, warm closing paragraph is far more effective than a passive sign-off.
Proofread before you send: Ask someone else to read it if you can. Reading the letter aloud is a reliable final check. Anything that sounds awkward to say will be awkward to read.
Keep it to one page: One page is the professional standard. If you cannot make your case within that limit, the issue is usually focus rather than word count.

What are the most common cover letter don'ts?

Up to 81% of hiring managers say they have rejected applicants after reading their cover letters (Resume.io Cover Letter Statistics, 2025).

Most of those rejections come from the same avoidable errors.

Do not send a generic letter: Hiring managers can identify a copied-and-pasted template immediately. A generic letter signals that the role is not a priority for you, which makes it easy for them to move on.
Do not repeat your resume: The cover letter is not a prose version of your work history. Restating what is already on the page wastes the reader's time and misses the real opportunity, which is to add depth and context.
Do not make it about what you want: Every paragraph should answer the question: what can you bring to this employer? Explaining how the role suits your lifestyle or career goals does not help your case at this stage.
Do not criticize a previous employer: This is one of the clearest red flags in any application. Speaking negatively about a past company or manager raises immediate doubts about your professionalism, regardless of how justified the criticism may be.
Do not use overly informal language: A cover letter is a professional document. Slang, forced humor, and casual phrasing can read as poor judgment rather than personality. Keep the tone warm but measured.
Do not mention salary expectations: Unless the job posting specifically asks for them, leave salary out entirely. Raising it at this stage shifts the focus away from your suitability for the role.
Do not apologize for missing qualifications: Drawing attention to what you do not have is never a good use of limited space. If you are applying, make the best case you can with what you do bring. Concentrate entirely on that.
Do not exceed one page: A letter that runs over a page suggests an inability to edit. It places an unnecessary burden on a reader who is likely reviewing many applications at once.
Do not stuff in keywords: Including relevant terms is sensible, but overloading the letter with them makes the writing feel hollow and formulaic. Natural, specific language outperforms a list of buzzwords every time.
Do not skip the final check: 58% of employers discard cover letters that contain obvious mistakes (Resume.io Cover Letter Statistics, 2025). Even one error in a professional document can suggest carelessness, and in a job search, first impressions carry significant weight.

Most of these mistakes are easy to fix once you are aware of them.

The fact that you are thinking about them now already puts you ahead of a large portion of applicants.

Pink block with red cross cover letter d's don'ts

What are some common mistakes to avoid in cover letters?

The don'ts above cover what not to do strategically.

The mistakes below are different.

They are errors that happen in the writing itself, often in letters that are otherwise well-intentioned.

Starting with a weak opening line: The first sentence of your cover letter is the most valuable on the page. Many applicants waste it on something like "I am writing to apply for the position of..." which tells the reader nothing useful. Start with something that immediately demonstrates fit or value.
Getting the salutation wrong: Try to find the hiring manager's name before you write. If you cannot, "Dear Hiring Manager" is a professional and widely accepted alternative. Misspelling a name or using the wrong one entirely is a serious error that signals a lack of care. Phrases like "Dear Sir or Madam" and "To Whom It May Concern" carry the same problem and are worth avoiding for the same reasons.
Using adjectives without evidence: Calling yourself "driven," "passionate," or "detail-oriented" adds nothing without a supporting example. Every quality you claim in the cover letter should be grounded in something real, a result, a decision, a situation, even a brief one.
Focusing on job title and education rather than impact: Listing your credentials tells a hiring manager what you have. Explaining what you did with them tells them who you are. That second layer is what the cover letter is for.
Writing a letter that could belong to anyone: If you removed the company name and job title from your letter and it would still make sense sent to a dozen other employers, it needs more work. Specificity is what makes a cover letter persuasive and what makes it memorable.

What are the three golden rules for writing a cover letter?

If you apply nothing else from this page, these three principles will put you ahead of the majority of applicants.

1. Tailor it every time: A tailored cover letter written for this role, at this company, in response to this job description will always outperform a general template. The personalization does not have to be extensive. A well-chosen sentence or two that references the employer's specific context can be enough to signal genuine interest.

2. Focus on what you bring, not what you want: The moment your letter shifts to what the role offers you, the salary, the progression, the location, it loses its purpose. Keep every paragraph anchored to what you can contribute.

3. Keep it short and precise: One page, three to four focused paragraphs, a strong opening, and a clear close. Restraint in a cover letter is not a limitation. It is a signal that you know how to communicate efficiently, which is itself a quality worth demonstrating.

How long should a cover letter be?

A cover letter should fit on one page, around 250 to 400 words across three to four paragraphs.

Recruiters are reviewing multiple applications at the screening stage and do not have time for more.

A concise letter also demonstrates something useful in itself: the ability to make a point without padding it.

If your letter is running long, cut the weakest paragraph first.

For full guidance on spacing, fonts, and layout, the cover letter format guide covers the practical details.

Key takeaways

A tailored cover letter that focuses on the employer's needs rather than your own gives you a meaningful advantage at the screening stage.
The most damaging mistakes are all avoidable: generic letters, resume repetition, errors, and missing keywords are the reasons most cover letters fail.
Three principles cover most of what matters: customize it every time, focus on what you bring, and keep it to one page.
A strong closing call to action is as important as a strong opening. Both shape how the hiring manager remembers your application.
Errors in a cover letter carry a high cost. One final proofread before submitting is always worth the time.

Frequently asked questions

The questions below cover the most common points of uncertainty around cover letter dos and don'ts.

What should you not put in a cover letter?

Do not include salary expectations (unless specifically requested), personal information unrelated to the role, criticism of a previous employer, apologies for missing qualifications, or anything that duplicates what is already on your resume.

The letter should focus entirely on what makes you the right fit for this specific role.

Is it bad to not include a cover letter?

It depends on the application. When a cover letter is genuinely optional and the posting makes that clear, a strong resume can stand on its own.

In competitive roles, however, a well-written cover letter can be the reason a borderline application gets a closer look, and skipping one when it is expected is a significant disadvantage.

What are the worst things to say in a cover letter?

Avoid clichés that carry no information: "I am a hard worker," "I am passionate about this opportunity," "I think outside the box," and "I feel I would be a great fit" are phrases that appear in thousands of letters and add nothing.

Less obvious but equally damaging: opening with what you hope to gain from the role, explaining that you are not fully qualified but willing to learn, or referencing the company's salary or benefits before you have been invited to interview.

4.7

50 people rated this article

Click to rate this article

Post

Written by

Paul Drury, Content writer / HR Specialist

With a decade’s experience of writing about job search and recruitment topics, Paul understands the power of words to influence mindsets and alter destinies. His previous recruitment career taught him that the seeds of a successful job search are sown long before you come to writing your resume. Dad of two great teenage kids and husband to a long-suffering writing widow.