What NOT to do in the Interview!
For fun, emotional security and the thrill of anticipation, the job interview ranks right up there with IRS audits and root-canal work. When you are among 400 applicants for one super job, it's a lot like musical chairs. Winning just means surviving until the last round when everyone else has been eliminated.  So stop worrying about how to do something outstandingly right.

A big part of interview success is being careful not to commit obvious wrongs. Avoid these mistakes and you're far more likely to find yourself in the job-search finals. These helpful hints on job interviewing mistakes should help you make the best impression.

1.   Arriving Late.
Nothing makes a worse impression. If you can't turn up on time for the interview, what on earth would you do as an employee? If there's even the remotest chance that weather, traffic or hard-to-follow directions might be a problem, leave absurdly early just to be sure. If your car is hit by a meteor, go to a phone booth and ask to reschedule.
2.   Arriving Early.
Getting to the office building at 3:30 for a 4:00 appointment is good; presenting yourself to the receptionist at that time is not. As Jeffrey G Allen explains in How To Turn An Interview Into A Job (Fireside, 1983), "When it comes to interviewing, only fools rush in." It pressures the interviewer - and could make it look as though you have nothing better to do than read magazines in the waiting room. Instead, go to a nearby restaurant for a last-minute cup of coffee and a final check of your hair and clothing.
3.   Dressing Wrong.
Speaking of clothing, it matters. How you look has a lot to do with how you're seen. "Oftentimes in the very first few minutes of the interview, the decision is made whether it's going to be a turndown or a second interview," stresses John L. LaFevre, a human resources director based in Ohio and author of How You really Get Hired (Arco/Prentice Hall Press, 1986). "It either clicks on or it clicks off, and the remainder of the interview is spent validating that early judgment." Dressing too casually or flamboyantly can ruin your chances. The safest choice for any interview is a tailored suit in a conservative color like navy, gray or tan. Even the executives in wildly creative fields (TV, music, advertising, etc.) will respect you for knowing that a job candidate should look businesslike.
4.   Dressing In A Rush.
Don't. If you select your clothes right before you leave, you won't have time to fix the loose button or scuffed shoe you've just discovered. On the job interview, neatness counts more than it has since your last grade for penmanship. Try on your entire interview attire the night before the appointment, if not earlier. That way you can make any necessary improvements or repairs.
5.   Smoking.
In one Seattle University study, up to 90 percent of all executives surveyed said they'd hire a nonsmoker over a smoker if their qualifications were equal. Anyway, smoking makes you look nervous.
6.   Drinking.
Even if this is a lunch or dinner interview and others are ordering cocktails, it's better to stick to mineral water or club soda. At the very most, ask for a white wine spritzer (a tall glass of wine and club soda on the rocks) and don't have more than one. You need to be alert for this experience, not mellowed out.
7.   Chewing Gum.
Gum is not a good substitute for cigarettes or self-confidence. Gum chewing looks appropriate only in vintage movies.
8.   Bringing Along a Friend or Relative.
Tempting though it may be, resist the urge to bring someone along to hold your hand or help you fill out applications. Even being seen saying goodbye to your best friend or your spouse at the building door can make you look as if you didn't have the nerve to get there on your own. Being picked up afterward also reeks of dependency.           
9.   Not Doing All Your Homework.
It isn't necessary to memorize the company's annual sales and profit figures, but you should know something about their products or services. One candidate lost out on an AT&T interview by mentioning their involvement in a news story that had been about ITT, and there was no way for the candidate to regain credibility after such a glaring error. Check out information about large companies in business magazines or corporate directories at your public library, or call the company to ask for a copy of the annual report. For smaller organizations you may have to rely on the grapevine; some of the best information can come from people who used to work there.
10.  Skipping A Dress Rehearsal.
You wouldn't make a speech to your PTA or church group without planning what you're going to say, yet people walk into job interviews every day just assuming that brilliant words will leap to their lips. Don't assume. Make a list of the questions you'd ask if you were interviewing someone for this job then rehearse the best possible answers using a tape recorder and/or a friend for feedback.