You may look good on paper or in your interview suit, but if you're looking to nail your big interview, looks aren't everything. How you sound is often more important. But many job seekers let careless speech habits sink their chances of landing that plum job.

Here are six common language mistakes and how to keep them from sabotaging your interview:

1. Nonwords

Filler words such as "um," "ah," "you know," "OK" or "like" tell the interviewer you're not prepared and make you sound like a Valley Girl (or Boy). A better strategy is to think before you speak, taking pauses and breaths when you lose your train of thought. Everybody utters an occasional "um," but don't let it start every sentence.

2. Up-Talk

A singsong or rising inflection at the end of every sentence creates a tentative impression and makes it sound as though you're asking a question instead of making a definitive statement. You need to speak with conviction when selling yourself in an interview. Bring your intonation down when ending a sentence to avoid talking up.

3. Grammatical Errors

The interviewer may question your education when you use incorrect grammar or slang. Expressions such as "ain't" "she don't," "me and my friend" and "so I goes to him" aren't appropriate. Be sure you speak in complete sentences and that tenses agree. The interview is not the venue for regional expressions or informality.

4. Sloppy Speech

Slurring words together or dropping their endings impairs the clarity of your message. To avoid slurring and increase understanding, speak slowly during an interview. Make a list of commonly mispronounced words, and practice saying them into a tape recorder before the interview. Some common incorrect pronunciations include "aks" for "ask," "ath-a-lete" for "athlete," "wif" for "with" and "dree" for "three."

5. Speed Talking

While everybody is a bit anxious during an interview, you don't want your information to fly by like a speeding bullet. A rapid speaking rate is difficult to follow, and speed talkers are seen as nervous. Slow down your racing heart by doing some breathing exercises before the interview. To avoid rushing, listen to the question, and then count two beats in your head before answering. When you finish a sentence, count two beats again before continuing. Don't be afraid of silence. Pausing is an effective communication technique. The interviewer needs a few seconds to process what you just said anyway.

6. Weak Speak

Wimpy words modify or water down your conviction and in the end your position. When you pepper a conversation with "hopefully," "perhaps," "I feel," "kind of" and "sort of," the message you convey is a lack of confidence. Use power words such as "I'm confident that," "my track record shows," "I take the position that," "I recommend" or "my goal is." The language you use gives the listener an impression about your level of confidence and conviction.

The Bottom Line

You don't have to study elocution to speak well. Simply slow down, take time to pronounce all the syllables and leave slang at home.

Companies want job candidates who are well-spoken and articulate, and recruiters won't represent a job candidate if they don't match the client's profile. According to Lori Zelman, vice president of human resources at Strategic Workforce Solutions in New York City, "The people most highly sought after are the ones who are succinct in the explanation of their work experience."

[Diane DiResta is the author of the public-speaking best-seller, Knockout Presentations: How to Deliver Your Message With Power, Punch, and Pizzazz, and the president of DiResta Communications, a New York City speech coaching and training firm.]