There are many things in life you can do multiple times. Making a first impression on someone isn't one of them.

First impressions are lasting. Once a first impression is made, if it's less than great, it takes a long time to change it.

Experts say it takes between five and 15 seconds for someone to form a first impression. According to William Thourlby in his book "You Are What You Wear: The Key to Business Success," the first time we meet someone, we're trying to size them up. People look at socioeconomic status, level of education, social position, level of sophistication, economic background, social background, moral character and level of success.

First impressions are influenced by our backgrounds, including our families, friends, education, religion, jobs and other factors. These include body language, dress, appearance and voice. Your body language and appearance speak much louder than words. Use your body language to project appropriate confidence and self-assurance. Stand tall, make eye contact, greet with a firm handshake.

One of the most important and terrifying times to make a spectacular first impression is when you are interviewing for or starting a new job.

Even if you never plan to leave your current job, you will probably be promoted or switch to a new position at some point, and the experience will be much the same. Keep in mind these guidelines for relieving Day One stress.

• Don't be late. In fact, it's best to be a little early. Double-check where you are supposed to be and what time you are expected to start. If it's a new workplace, test your route and give yourself extra time.

• Learn the lay of the land. Your manager will probably show you around, but make an extra effort to remember what you see so you don't have to repeat questions. Yes, you can always ask for directions later, but you'll impress people more by being a quick study.

• Master people's names. You will gain a reputation for attention and thoughtfulness by memorizing the names of everyone you meet. There are a variety of strategies to help you match names and faces.

• Bring your lunch. Maybe the boss or co-workers will take you out to lunch on your first day, but don't count on it. Stay in the workplace and eat in the lunchroom so you get a chance to meet more people. Then demonstrate your eagerness to get back to work.

• Smile. Be friendly. Show that you're glad to be there. People respond to smiles and sincerity. Ask questions and be interested in your new co-workers. They will remember and appreciate your effort.

• Restrain your instincts. Your first day is a time to learn, not to show off what you think you know. So, show you are glad to be there, but don't let your enthusiasm get the best of you, lest you come across as insincere. Concentrate instead on what you can contribute and how you can fit in to the culture.

On the other side of the equation, when I hire people, I am acutely aware of the first impression they leave on me. Will a customer have the same reaction?

Mackay's Moral: You never get a second chance to make a good first impression.

Harvey Mackay is a Minneapolis businessman. Contact him at 612-378-6202 or e-mail harvey@mackay.com.