You've polished your resume and conducted thorough research on the company you want. You've done all the things experts recommend to make yourself a shoo-in for the job. Yet no matter how many boxes you check off, your phone still isn't ringing. What are you doing wrong?

No matter how far you progress up the career ladder, even if you've owned your own company and spent years hiring people, you'll likely find yourself on the other side of the hiring desk again someday. Unfortunately, there's never a guarantee you'll be hired, even when you're sure you're perfect for a job.

But when you've unsuccessfully endured multiple interviews, it's only natural to wonder where you're going wrong. Since hiring managers will often only use language like, "We decided to go in a different direction," it can be nearly impossible to find out why you weren't chosen.

Here are a few things hiring managers won't tell you about why they marked you off the list.

1. You seem too eager.

Job searches can take months, and often you won't hear back. At the very least, you'll often be forced to wait weeks to hear back after an interview. When you do hear back, it may just be through a form email. Over time, it can be easy to feel frustrated, especially if you've interviewed for multiple openings without hearing back.

Brush it off your shoulders and keep moving forward. Show healthy interest during an interview, but don't be too eager, or let desperation show, if there is any. Don't let any struggle with the job search find its way into your interaction with prospective employers.

Also, avoid burning bridges with employers who choose another candidate over you. You never know when that very employer will need to hire someone else in the months that follow and if you're gracious, you may move to the top of the list.

2. You don't have enough confidence.

Many of the top body language mistakes you can make signal a lack of confidence. Poor eye contact, a weak handshake, and bad posture can all send the message that you don't believe in yourself. If you don't believe in yourself, how can you expect an employer to commit to paying you a salary?

Sit up straight, smile, and answer each question assertively. Boost yourself up before each interview by telling yourself you are the right person for the job. Your positive attitude will definitely show.

3. You have too much confidence.

Too much confidence can easily cost you a job as well. This includes walking into the interview so sure of yourself that you completely fail to prepare.

Your goal should be to sell the employer on why you're the perfect candidate, sure, but you should also show respect to the interviewer by being friendly, professional, and ready to demonstrate that you're the perfect fit for their existing team. This includes asking questions about the job in addition to showing that you fully understand what the company's mission is.

4. You're just too good-looking.

There has been a long-held belief that more attractive people have an edge in job searches. Some studies have even confirmed that belief. But one recent study found that attractive women were more likely to be discriminated against when applying for less-desirable positions.

Studies from as far back as 1979 have confirmed this bias for other types of work, including managerial positions in male-dominated industries like construction. The discrimination appears to be mostly limited to women in fields where hirers stereotype them as not being fit for the occupation. 

5. You use demanding language.

No matter how many negative interview experiences you have, you're still in the position of selling a company on committing to you. Cover letters and interview statements that include demands will actually send you straight in the "no" pile.

Avoid issuing ultimatums such as, "I expect an answer within two weeks." Your tone should always be polite, thanking the hiring manager for considering you for the position, rather than taking the tone that they're lucky to have the chance to speak to you.

Looking for a job is rarely easy, but with this list of things to avoid, you can tackle your job search with renewed enthusiasm. Whether it's your first or 50th job interview, make sure you greet each potential employer with a bright smile and an eagerness to discuss your qualifications.