3. Not listening.

In inability — or unwillingness — to listen well proves that you are self-oriented or lack discipline. No one wants to buy from someone who doesn't care about what they say enough to listen.

4. Leading with your product.

Unless you are Apple, you're not Apple. Trying to open an opportunity by leading with your product mostly causes resistance. It also makes it appear that what you sell is a commodity.

5. Competing on price.

Unless that is your company's chosen strategy, competing on price is one of the worst of worst practices. It normally doesn't work. And it prevents you from delivering.

6. Lying or not setting the right expectations.

There aren't too many things worse than lying in an attempt to win business. Lies of omission aren't any less harmful, which is why you have to set the right expectations, even when you feel that it will threaten your deal.

7. Failing to follow up.

Failing to keep your commitments might indicate that you don't care, that you aren't detail-oriented and buttoned-down, or that you can't be trusted. Even the small commitments matter.

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8. Avoiding accountability.

When you sell something, you own the outcomes you sold. Avoiding accountability makes you someone who can't be trusted to be part of your client's team. Not owning what you sell makes it almost certain you don't make a future sale.

9. Possessing a poor mindset.

Having a negative or cynical attitude is a terrible affliction. Spreading that disease is even worse. Your results begin in your mind, and a poor mindset is the foundation of poor results.

10. Giving up.

A lack of perseverance and a willingness to professional pursue your dream clients will massively limit your success in sales. You can train your dream clients that you will go away and that they can wait you out.

11. Choosing the wrong medium to communicate.

Sending an email instead of a phone call when a critical conversation is necessary is a surefire way to damage a relationship. When an issue is important, the wrong medium says you don't care, or you are avoiding the difficult conversation.

12. Living in your inbox.

Email isn't your job. The most important work you need to do isn't done in your inbox. You will never be as productive as you could be if you allow other people's priorities to replace yours.

13. Failing to grow personally and professionally.

The name of the game is business acumen and situational knowledge. If you want to be a trusted advisor, then you need the trust, and you need the chops that make you someone who others will allow to advise them. If you aren't growing, you're shrinking.

14. Making excuses.

Excuses suggest that there is nothing you could or should be doing differently. But if you aren't getting the results you want, you need to do something differently, don't you? Excuses are your attempt to rationalize your poor results and absolve you of responsibility. Making excusesfor your failure or losses disempowers you.