Sometimes people take themselves out of the running for a job before they even apply.
Maybe the ad for the position asks for experience they don't have or a skill they are missing. Sometimes people don't apply for a job simply because it asks for a certain amount of years in a similar position.
While any of the things in a job listing may prevent someone from getting hired, a lot of times that's not the case. Instead of someone not applying for a job because they're not the perfect candidate, it's better to have thick skin and be prepared for rejection, but also ready to make your case.
Take a realistic approach
If a job requires a degree or certification for legal reasons and you don't have it, you're not likely to get hired. For example, a hospital looking for a chief surgeon won't take kindly to your cover letter that says, "While I don't have a medical degree, I'm a fast learner, who can think on his feet."
It's reasonable to apply for jobs you know you can do when the ad does not outline your particular skills. If you're making a realistic judgment that you can do the job, and there's no legal reason to not hire you, then it's up to you to change minds.
Make your case
When you apply for a job where your qualifications are not obvious, it's important to connect the dots for the person doing the hiring. Make your case in your cover letter and address how you can do the job despite not having some of the skills or experience asked for.
Be specific and avoid vague terms like saying you are "good with people" or "you can learn new skills quickly." Explain how your past qualifies you for the job and detail how you will obtain any missing skills. For example, if a job requires a certain certification that you don't have, be direct in how you plan to correct that. For example, "While I'm not a licensed Realtor, I am currently taking a certification class and expect to be certified by the end of October."
It's also a good idea to highlight areas where you have strengths that someone with traditional qualifications may not. For example, if you have been a manager, and the job involves managing, you may be able to handle it better than someone making the leap to managing even if they have more experience in the field.
Believe and prepare
If you land an interview, your fight has only just begun. In a number of situations, I have been brought in for interviews as what I would call the novelty candidate. The company had no plan to hire me but wanted to have a certain amount of candidates.
When that happens, basically the door has been left ajar for you and it's your job to open it all the way. It's a situation where your interview has to blow people out of the water.
For one job I did land in that situation I presented my interviewers with a full plan for my first 100 days in the job. I laid out deliverables and how they could judge my success or failure. In another case, for a position I did not land, I created handouts with mock-ups for how I would change their website, along with a detailed plan for what I would do in the job.
Both were bold plays and one impressed my future bosses while the other mildly offended my potential employer by pointing out what they were doing wrong. Basically, I approached each situation as a swing for the fences. I knew I could do the job, so I took every chance to show the hiring person that I would not only be able to handle the position but that I would thrive in it.
You can do the same thing as long as you truly believe you can handle the job and you put in the time to prepare for your interview. Go in and show the people doing the hiring that any supposed shortcomings are more than made up for by your strengths, and your can't-be-defeated attitude.