There are many ways to destroy your chance of an offer, or even getting them to keep your resume on file. They can run the range of showing up with alcohol on your breath to getting in a fistfight in the parking lot. There are, however, many common mistakes that well prepared candidates make repeatedly from one interview to the next. Knowing what these are will keep you aware of what not to do, ever, during an interview.

Dressing unprofessionally will put you immediately on the wrong foot. Dress casual is not appropriate, even if you have heard that it is casual Friday at their office. You must put your best foot forward on the day of the interview. The people that are meeting with you need to be able to judge how you will look on Monday morning and how you will represent their company to customers and other staff. It is much better to appear as an example that they may want for other employees in the office.

Do not appear too nervous during the interview. Tapping your foot or playing with your pen is a sign of someone who may have difficulty under pressure. You should prepare in advance by rehearsing the interview questions and answers to avoid panic. Control yourself by taking notes and asking questions.

Do not make self deprecating remarks like you know that you are over or under qualified. Let them make that decision otherwise you are letting them know up front that you desperate for the job. If no one else wants you, why should they? They want you to be excited about working for them and respectful of the opportunity. Most importantly, they want to feel as though your decision to accept an offer is based on the knowledge that the position and compensation suit your needs, not your willingness to take the first offer down the pike. That does not make for a long term commitment or a happy employee, both of which they desire.

Do not bring up subject of compensation. If you seem more interested in the vacation time and salary than in the position itself, the interviewer will not take you seriously. Yes, they plan to pay you for your work and may throw in some great perks. But find out what you will be doing first. In that vein, don't let them bring up salary too early, either. Defer by saying that you do have some thoughts in mind, but that you would like to discuss the position first. You need to be able to sell them the product and make them want you before handing them a price that may be higher than they anticipated. In the best case, the interviewer will finish with discussion of the salary. They may ask you what you have in mind, so put the ball back in their court be replying with your current or last salary. They should respond by telling you what range the position offers. Then answer honestly whether or not that range will allow you to comfortably take the position. If the interviewer never brings up the subject of compensation, then leave without discussing it. When they make their offer, they may have you negotiate at that time and possibly with someone else.

Lastly, not asking any questions is the most common, and most detrimental, mistake made. It may be that you do not have any. Your interviewer may have talked ad infinitum about themselves, the position, and the company. Prepare for this in advance by creating a list of questions to ask. You should make notes while they are speaking and highlight an area that you may want to go back to. Think of questions that are unlikely to be discussed during an interview, such as "Why do employees leave this company?" as a backup for this situation. Not asking questions makes you seem disinterested or unprepared, and you do not want to seem either, ever, to an interviewer.