The job interview mistake I didn't even know I was making.

I had no idea how bad it was until my co-workers gasped when I told them.

Job interviews are a tricky game to master.

You need to be confident, but not cocky.

Eager to please, but not desperate.

Not over-dressed, nor under-dressed.

Most aspiring professionals have a reasonable idea of how to conduct themselves in an interview. But you don’t want to be blindsided by mistakes you didn’t realise you were making.

Here are some such examples:

1. Overdressing

Dress for the job you want, right? Wrong.

“Presentation” plays a bigger role than most employers — and certainly, job seekers — would care to admit.

This doesn’t mean you need to dress for a black tie gala.

Wearing a suit and tie to an interview at a media start-up is less likely to win you points, and more likely to give the impression you don’t fit in with the team and values.

Read the culture carefully, my friends. If in doubt, smart casual is the way to go.

NB: Jeans of all kinds are outlawed. If you’re lucky and work hard, you may someday earn the right to wear jeans in your workplace.

Related content: 11 ways a job interview is like a first date. (And how to nail them both.)

2. Talking yourself up too much

Business Insider recently ran a story about a guy who submitted a ‘relevant resume’ — a CV that listed all of his failings instead of his successes.

As it turned out, detailing his attributes earned him zero interviews and a single response — he received eight positive responses to the relevant resume.

Maybe the ‘relevant resume’ isn’t such a great idea if your flaws include perpetually being late or having a lengthy criminal record.

But there’s a lot to be said for recognising your mistakes and vowing never to make them again.

Having your ‘opportunities for improvement’ in mind will also help when your employer ask the dreaded question about your weaknesses.

3. Taking food and drink into your interview

Confession: I have committed this sin.

I went for a job interview, arrived early, thought “hey, I could use a coffee,” and then took it into my interview.

I was extremely fortunate my new boss gave me the job, later confessing he thought the coffee was a sign of my confidence.

Just this week an employer blasted an interviewee for taking a milkshake into their interview.

Lesson: Unless your interviewer asks you to coffee, don’t bring one in. It’s actually quite rude.

4. Arriving early

Don’t get me wrong — arrive early. Just not too early.

Rocking up more than 15 minutes before your scheduled appointment probably won’t work in your favour. It will, however, risk making the interviewer feel uncomfortable about having to rush to your side.

Don’t you have better things to do than sit in a reception area for half an hour?

This is the question your employer will be asking — you should too.

Related content: “I did not get my job on merit. And neither did you.”

5. Pretending you understand everything.

Not making a fool of yourself is probably at the top of your mind during a job interview.

But don’t let you fear of making a mistake stop you from engaging.

For some, not asking questions in a job interview can come across as being disinterested. If you ask a question it will show the employer you’re invested in the organisation.

Don’t play it too cool. Prepare at least one question to ask your prospective boss.

What are your job interview tips?

Related content:

Why ‘leaning out’ at work is a terrible idea.

How to make your CV look impressive. (No graphic design required.)