9 mistakes that will instantly destroy a first impression, according to these self-made millionaires

Last month, nine self-made millionaires and Advisors in The Oracles told us how they dress to make a good first impression.

But first impressions go far beyond what you wear. So we asked them about the common mistakes people make that can instantly destroy a first impression — and how to change those bad habits once and for all.

"I never hire anyone I don't trust, and I always form my first impression of someone based on their eye contact. If you want someone to trust you, you better look them straight in the eye.

A good handshake is also key. It isn't so much about firmness, it's about making sure the skin between your thumb and forefinger connects with the other person's hand in the same spot. That connection signals that you're confident and trustworthy."

—Barbara Corcoran, founder of The Corcoran Group, podcast host of "Business Unusual," investor on "Shark Tank."

"Kindness goes a long way. I still remember all the show business folks who were mean to me early in my career, as well as the ones who took my hand and gave me advice. 

I once hung out with a friend who was a big celebrity, and a fan approached him for an autograph. When he gave it to them without even turning around to look at them, I saw the hatred on his fan's face."

You never forget kindness, but you often hear things like, 'I got in an elevator with so-and-so, and they didn't even say hi.' Now they hate that person for the rest of their life."

—Jay Leno, comedian, star of CNBC's "Jay Leno's Garage," former host of NBC's "The Tonight Show. Follow him on Facebook and Instagram.

"To build rapport and credibility quickly, ask open-ended questions.

For example, find out how the other person got started in their industry or ended up in their job role or city. Ask about their goals and dreams to see how you can help them, with questions like, 'Where do you want to be in 10 years?'

You'll get to know the person better, communicate that you're thoughtful and curious, and grow your knowledge."

—Marla Beck, co-founder and CEO of Bluemercury, creator of M-61 Skincare and Lune+Aster cosmetics.

"A first impression doesn't start the second you meet someone. It begins with your reputation, which you build over time with above-average performance. Then when you finally meet that person, your reputation precedes you."

 —Markus Hetzenegger, founder and CEO of NYBA Media GmbH. Follow him on Instagram, LinkedIn and Facebook.

"It's not enough to be interesting. You have to be interested. Why? Because what really drives a person is themselves. So make your conversation about them.

Ask what they do, why they do it, and what they want to accomplish. Save your pitch on how you can add value to their lives for future encounters, which you'll get if you don't blow the first one.

And don't forget to give them your business card — ideally with your picture on it — so they have a way to follow up with you. But remember: It's ultimately your job to follow up with them."

—Natalie Workman, co-founder of Cardone Ventures for Women. Follow her on LinkedIn, Facebook and YouTube.

"When you're humble and generous, you'll build a loyal community around you. It's a give-and-take in the business world, but we must first learn to give. The more you can offer your services, knowledge, connections, and time to others, the more they will give in return."

—Ashley Alderson, founder and CEO of The Boutique Hub and Boutique.Style, cancer survivor, motivational speaker, host of "Boutique Chat." Follow her on on Instagram and LinkedIn.

"I'm enthusiastic by nature, but I used to hold back because I wanted to seem 'cool' — until I realized my enthusiasm is actually one of my most valuable assets.

It's so important to identify your strongest skills and showcase them proudly. If you're an eloquent speaker, speak often. If you're a great listener, ask lots of questions. But you also need to avoid overemphasizing them.

—Alon Rajic, CEO of Finofin, which operates Money Transfer Comparison, a leading authority on the comparison of money transfer providers.

"Years ago, if I met someone new, I would act like I had valuable insight and quickly steer the topic toward what I could offer. Over time, however, I learned to listen more and only speak when the timing is right and when I have something genuinely valuable or insightful to say."

—Craig Handley, co-founder of ListenTrust and author of "Hired to Quit, Inspired to Stay."

"The poet Maya Angelou once said, 'People will never forget how you make them feel.'

Those words are so true. I've been offered great opportunities in the first meeting because someone 'had a good feeling' about me. My strategy is be my most authentic self, instead of trying too hard to impress them (which is something I see so many people do)."

—Andrea Callanan, musician-turned-entrepreneur; voice, confidence, and success coach, author of "You Are Meant for More," and founder of employee engagement company Inspire Me. Follow her on Facebook and Instagram.

The Oracles is a mastermind group of the world's leading entrepreneurs who share their success strategies to help others grow their businesses and build better lives. For more, follow The Oracles on Facebook, Twitter, and LinkedIn.

Don't miss:

• 10 mistakes that rich and successful people never make, according to these self-made millionaires
• Here's an example of the perfect answer to 'Tell me about yourself,' according to Yale career experts
• Warren Buffett calls this 'indispensable' life advice: 'You can always tell someone to go to hell tomorrow'

Like this story? Subscribe to CNBC Make It on YouTube!