Everyone knows (or should know) the big things that can cause an interview to completely tank.  However, there's also some smaller little things that interviewees do that give interviewers an "oh, I think we'll pass." feeling.  If you want to get hired—best to avoid these gaffes:

1.     Going into an interview without anything.  Always bring a notebook or a folder with paper, extra copies of your resume (trust me, the printouts from Monster.com are a mess) or a small, professional briefcase to pack these things in.  Also—always make sure you have a pen.  Sounds so simple, but it's easy to leave the house without them.  Arriving at an interview without them tells an interviewer that you're just planning on "winging it", and that you don't anticipate the need to jot anything down to ask about later.  Kind of like when a waiter arrives at your table without a pad.  You assume he'll care enough to remember your order correctly when he gets back to the kitchen, but you're not always sure. You want an employer to always feel sure about you and your abilities.

2.     Saying anything remotely negative.  This should be implied to include past employers as well (which everyone knows).  Let's say that in your last job you spent the majority of your time on the phone with clients and customers.  In your mind—you'd love to get a job where you're off the phone and in front of them more.  You're happy because the job you're interviewing for sounds like it includes a lot more facetime.   In the interview, an interviewer asks why you're looking to leave your past job.  You start to talk about how much you don't like being on the phone for the entire day.  What you don't know about the job (and don't assume the job description is a complete inventory of all components of a job) is that before you can meet with all of those clients face to face, you'll need to spend the mornings for the first 3 months making calls to current customers to set up those meetings and establish a relationship.  So while the new job does allow you to get out and mingle—there'll be time spent on the phones in the beginning.  The employer hasn't been secretive.  You made an assumption. The solution? Don't ever say how much you dislike anything.  Ever.  In the case of the above example, say that you'd prefer to spend more facetime with clients.  Your current job just allows for phone conversations, not travel, but you would appreciate the opportunity to travel and meet with people face to face.  You never said you hated being on the phone with the heat of a thousand suns, just talked about how much you'd appreciate talking to them face to face. 

3.     Look tense.  Come on, you can handle this one.  I know you're going to be nervous, the employer knows you're going to be nervous and you know you're going to be nervous. However, acting nervous and tense makes the interviewer nervous and tense.  Remember that they're trying to assess if you can do the job and if they like you.  I have interviewed but not hired people who sat stiffly in my office because I figured that they'd be stiff to work with, and I'm not a stiff person.  Before you walk into the interview, listen to your favorite music (theme song from Rocky?) and remember that being likable and competent goes even further than just being competent. 

4.     Fake knowledge you don't have.  If they're looking for experience in a particular field or with a particular computer program—your first instinct may be to say that you have worked on it or "played around" with it, when maybe all you did was pick up the box in the computer store.  It's OK to ask them if it's similar to a program that you do know, and give them some examples of programs you've learned at other jobs in relatively short timeframes.  Remember if they're looking for an egg and you're a chair, it's never going to be a fit and it isn't anyone's fault.  If it's something that you're seeing as a requirement on quite a few of the jobs you're applying for, then you do need to take a class to learn it.  You never need to "fake it until you make it." 

Those are some of the basics.  Remember to always be genuine and friendly.  Think of Julia Roberts, Oprah Winfrey or Will Smith when you prepare for interviews.  Keep in mind how they're nice, approachable, but never show their nervousness and always show their personality.  Friendliness will go far.