Boomer or millennial: What your CV should - and shouldn't - reveal

One small mistake could be holding your job application back, a resume expert has revealed.

Former recruiter Patrick Harnett, who is now a professional resume writer and career coach, said one of the most common – and costly – CV mistakes he saw was jobseekers including their date of birth.

But he said many jobseekers also often gave their age away indirectly.

"A big one I see is a lot of people thinking they have to list their date of birth, but that's a big no-no because it can lead to ageism. It's also against the law to ask [a jobseeker's] age, so don't list it down on your resume," he said.

"People ask why – and it's because if a hiring manager asks a recruiter or HR person to find someone aged 30 to 35, even though they shouldn't ask that, if you are 36 and apply, you could be absolutely ideal but you won't be brought in for an interview.

"Another mistake is mentioning age identifiers on your resume. If you have the year you finished year 12 or a list of employment going back to the 80s, that's going to reveal your age, so be very wary of putting down dates.

"A lot of people also use email addresses like joebloggs82@gmail.com – a lot of people tend to use their year of birth in their address, and it's a dead giveaway."

Harnett, who is one of the most recommended resume writers on LinkedIn, said another huge mistake was CV length and incorrect formatting.

"Because there are so many candidates out there nowadays and companies don't have the manpower to scan through every application, resumes are often sent to a computer for scanning before they get to a human being and if they are not compliant, they don't get through," he said.

"How do you know if you are compliant? Structure and formatting are the golden rules so no headers on your resume and no tables because scanners can't read them and the information that comes back gets jumbled.

"Use Word, don't save it as a PDF because when you try to copy and paste information from a PDF it can also come out jumbled."

Harnett said while there was no "strict answer" to the perfect resume length, most applicants should stick to two to three pages.

Another common but avoidable mistake is including a resume littered with spelling and grammatical errors.

"I've seen one guy write 's**t' instead of 'shift' twice on the first page ... people often also write 'manger' instead of 'manager' as it is easy to mistype," Harnett said.

And while your application should include some industry terminology, he said it is important to avoid "HR buzzwords".

"Never directly copy and paste the information in the job ad to your resume ... when everyone says they are a confident, motivated, self-starter and a team player, all those words are used over and over again and they start meaning nothing to the reader," he said.

Harnett, who has run his Perth-based Resumes for Dudes business for more than five years, said other errors include failing to list specific achievements for fear of sounding "cocky" and having "repetitive and redundant" career objectives which waste space.

He also recommended leaving out referee contact details unless the job ad specifically requested them.

"If you don't include your referee details, it gives you more control over the referee process," he explained.

"When the recruiter does ask for them, it means you can give your referees a heads up to expect the call, because a lot of people don't realise that if someone calls you and the number is not saved in their phone, they won't bother picking up."