There are a lot of different reasons why job-seekers cannot get a job. One of the most common mistakes applicants do that make employers choose someone else, is not knowing what you're worth or not being ready to evaluate one's education, experience and skills fairly.
The Biggest Mistake Job-Seekers Make
Probably the biggest (and the most common) mistake job-applicants do when negotiating a salary is focusing on what you feel you need or deserve rather than on your value and the value you being to the prospective employer.
A surprising number of people decide what salary to ask for based on what they'd like, what they need or what they guess the role pays. If you do that, you can end up severely undervaluing your work.
Do not use your mortgage payment or other bills as a reason you should be paid more. Employers may be sympathetic, but that is not a reason to provide more compensation. Instead, focus on the increased value you bring to the organization. Stress your unique qualities, experience, education or some other feature to demonstrate benefit to the company’s goals, vision or purpose.