Last week, I wrote about a career mistake that cost me $50,000. It was a very valuable lesson to learn and I've never made the same mistake again.

There's definite value in learning from mistakes. But how about avoiding them in the first place? Doing so can save you a lot of heartbreak - and money.

I've asked dozens of CEOs and very successful people about the mistakes they made. After a while, patterns emerge. Below are the top 5 I've heard. I spoke about them in a webinar I hosted with WorkItDaily. Avoid these and you'll progress much farther in your career.

1. Selling Yourself Short. Hello! This is exactly what happened to me and why I lost out on $50,000 worth of income. I didn't think I was good enough. With a few rare exceptions, we human beings are often our hardest critics. We tend to undersell our value. I now tell everyone I know who negotiates their salary raises to always bump up the amount by 10% - it's an inexact science but chances are, whatever you think you're worth, you're worth at least 10% more.

2. Letting Humility Overtake Courage. It is super important to be humble the more successful you become. However, there's a fine line to tread here. Sometimes we undervalue our skills and let the humbleness overtake our sense of selves (see #1 above). We believe that other people are smarter than us. We think people older or more experienced must know more than us. Kat Cole, the Group President of Focus Brands, told me a great story about how when she became President of Cinnabon, she deferred always to her older colleagues. After a while, she realized she wasn't really leading the brand. She was letting her humility overtake her courage to speak up and make decisions - and in the process, not doing her job properly. Don't let your humbleness become your crutch.

3. Focusing on the Money. Earvin "Magic" Johnson, the legendary basketball player, tells a great story about how Nike's founder, Phil Knight, offered him a stake in the company when it was just a startup. Johnson said that he was more focused on the money - not the equity - and in the process, lost out on probably hundreds of millions of dollars of stock gains. When making decisions, don't let short-term satisfaction - a lot of cash up front - overtake potential to earn more later. I see this play out a lot with people who debate whether to take a higher paying job now or a lower paying job that teaches them new skills. My answer almost always is to take the lower paying job that will give them new skills since it will increase their overall value to an employer.

4. Getting Too Emotional. How many times have you fired off a hostile email only to regret it the moment you hit "Send." Me! Whenever I have done anything out of emotion, I've almost always immediately face-palmed myself. When it comes to your career, you mustn't get emotional. Never make any major decision when emotional. Never email when emotional. Never discuss things when you are emotional. Doing so is almost always a mistake. Whenever you feel yourself getting too emotional, take a breath, walk away and come back when you've calmed down. You'd be surprised how quickly a short walk around the block or parking lot will change your perspective. 

5. Being "dead" to people. Kevin Ryan, the uber-entrepreneur and investor behind successful companies like MongoDb, Business Insider, Gilt Groupe, notes that whenever he interviews for managers, he makes sure that person is spoken highly of by others. If he ever hears things like "that person was terrible to work for,", he says that candidate is immediately "dead to me." In other words, your reputation as a good person is critical. A reputation takes years to build and only a second to destroy. Take the time to build a great reputation, someone that others enjoy working with and respect. Be aware of how you treat your colleagues, bosses and people who work for you. You'd be surprised how small the world is. People talk. Your reputation is as valuable as your credit score. It will determine whether you win that next job.