Are you looking for a new job? You've probably read lots of advice about how to perfect your resume and cover letter, how to prepare for an interview, and the follow-up message you should send afterward. But there may still be some tasks you're leaving undone, and those omissions could prevent you from getting an offer for the wonderful job you're dreaming of.

That advice comes from personal finance site GOBankingRates, which recently published 15 tips for landing your dream job. All of them are good advice, but a few are things that many people never think of, and can make all the difference. Make sure you're not making any of these mistakes:

1. Not knowing what your dream job is.

If you've looked through job listings with the goal to pick out the job you want, stop for a moment. Step away from those listings, close your eyes, and try to visualize yourself in the best job you can imagine. What do you do all day? Is it an informal, fast-moving workplace, or a stately, elegant setting? Large company or small one? Aggressively competitive or one big happy family? What are the most important rewards you get (besides your salary) for doing that job well?

The adage that you can't get what you want till you know what you want is especially true when it comes to employment. Will you be able to find a job with every single attribute you come up with? Probably not. But if you don't start out knowing exactly what you want, you're liable to be swayed by what others want, and by the potential employer who most wants you. You'll wind up with a job that fits someone else's dream instead of your own.

2. Relying on job listings instead of reaching out to employers.

Employment sites are a great way to find out who's hiring and what kinds of jobs are out there. They're also a great way to get lost in the crowd because when a really appealing job appears on one of those sites, a large number of people will respond. That doesn't mean you shouldn't apply for your dream job if you see it advertised--you absolutely should. But don't stop there.

You should also identify the organizations you most want to work for, and take the initiative by reaching out to them. Find out who the hiring manager is in the area where you want to work, and get in touch to ask for a few minutes of his or her time for an informational interview. (LinkedIn is a great way to find the right person, and often a good way to send him or her a message, especially if you can't find an email address.)

If you get the meeting, either in person, by video chat, or by phone, you'll want to let the hiring manager know about you and your experience, but it's more important to learn than to impress. Find out what qualifications are most important for your dream job, and ask if there's any particular training that would make you better prepared. Do this right, and next time your dream job opens up, rather than go through the hassle of posting ads to job boards and wading through a mass of responses, the hiring manager might just give you a call.

3. Forgetting to research your interviewer.

I'm assuming you have the common sense to learn everything you can about the company you're applying to before you show up for an interview. But remember to also research the person or people you'll be speaking with. Make sure to look at their LinkedIn profiles, but also their postings on other social media, including Twitter. Extra points if you learn about something the two of you have in common--perhaps you both come from the same state or own the same type of dog, or have kids the same age. You can mention this commonality in the interview to make a more memorable impression.

It's also worth taking a few minutes to find out if your interviewer publishes a blog, either a personal one or one on the company website. Take the time to read a few back posts. Letting someone know you've read what they've written is a great way to make a connection.

4. Failing to do a dry run.

What kinds of questions will you be asked, and what tasks might you have to perform in the course of your job interview? You should have some idea about the answers to those questions. The best way to find out is to tap an executive in the same industry and ask for a mock interview in which the interviewer asks you the same sort of questions he or she would ask of a candidate for a job like the one you're seeking.

You might get a different set of questions during your real interview, but going through a practice run should give you a sense of the themes that will be covered and alert you to areas where you may need to be better prepared. And you might just wind up with a job offer from your mock interviewer as well.

5. Not preparing thoughtful questions.

There comes a moment in every job interview where you get the chance to ask questions of your interviewer. You will be judged on those questions, so make sure you have something smart to ask when the time comes. This is one reason taking the time to do your homework and learn whatever you can about both the company and the interviewer is so important. The more you know about the company, the likelier you are to ask good questions that will make your interviewer think--and think highly of you. The less you know about the company and the interviewer, the likelier you are to ask a question that reveals your ignorance.

So take the time to do your homework, learn what you can about the company, practice your interview, and prepare a few thoughtful questions that reveal your knowledge of the company. Doing those few things will put you way ahead of most of your competition. It might be enough to make your dream job a reality.