Mark Cuban: wildly successful entrepreneur, savvy media presence, and source of great startup and leadership lessons.

But don't just take my word for it. Another guy who feels this way is Ed Reeves, co-founder and director of Moneypenny, the market-leading provider of telephone answering specialists with offices in the U.S., the U.K., and New Zealand. (Instead of having random people in a massive call center take your calls, Moneypenny assigns one person to your account.)

Here's Ed:

Mark Cuban is a billionaire tycoon.

Let's just take a minute to let that soak in.

Mark Cuban has the kind of wealth that every burgeoning startup and entrepreneur dreams of. He's also earned every cent of it himself. Listed on Wikipedia as an American businessman, investor, film producer, author, television personality, and philanthropist, the self-made mogul and star of Shark Tank founded his first company at age 25 and is currently estimated to be worth in the region of $3 billion.

Driven and determined, he knows what he wants and has the self-belief and ambition to make it happen. That makes him the kind of person every entrepreneur should listen to.

Here are six of the best business lessons you can take from his career:

1. Give it everything you've got.

The English have a saying: Give it some welly. It essentially means throw everything you have at it.

Cuban, like myself, is a firm believer in this premise when it comes to business: The harder you work, the greater your chance of success.

Sounds obvious, but it never fails to amaze me how many entrepreneurs I see fail or flounder simply because they haven't put the hours in. Cuban has been quoted as saying that one of the top reasons people fail is a lack of effort.

He's right. The cold, hard fact is this: If you don't give your business everything you've got, the chances are that it won't work. Setting up a business is like having a child; it requires all of your energy. Nurture it. Pour your heart and soul into it. The more you put in, the more you'll get out--it's that straightforward.

Never rest on your laurels, either. It's all too easy to relax when a little success comes your way, but there are hundreds if not thousands of like-minded entrepreneurs waiting in the wings should you lose focus.

2. Think forward.

I literally feel like pulling my hair out when I hear someone say, "But it's always been done that way." So what? For years we cleaned our homes with a dustpan and brush before someone invented the vacuum cleaner.

Being creative and having the ability to spot opportunities before anyone else is what makes us entrepreneurs. It's gold dust and the hallmark of a great entrepreneur.

Cuban once used a Henry Ford quote to illustrate this point perfectly, saying, "If I asked my customers what they wanted, they would have asked for faster horses."

He's right. The vast majority of people don't think further ahead than what they already know--and that's fine. The key to being a successful business owner, though, isn't about accepting the status quo. It's about challenging the norm, being disruptive, and seeing a gap where others don't.

If you wait for clients to tell you what they're looking for, you'll undoubtedly be too late. It's your responsibility to identify what your customers need and create it for them.

3. Sell a solution, not a product.

Cuban says selling for a reason is one of the most valuable lessons he learned as a young entrepreneur, and I wholeheartedly agree. Survey after survey has found people are far more likely to buy from someone they know and trust, and one of the best ways to create this trust is by offering a genuine, bona fide way to make people's lives easier--be that by solving a problem, saving people money, or improving their efficiency.

It's not rocket science. Just put yourself in your customers' shoes. Think about what you would want. It's a straightforward approach, but one that means your clients will view you as a partner rather than an annoying salesperson who won't stop calling.

4. Make work fun.

When my sister Rachel and I founded Moneypenny 15 years ago, there were many things we didn't know: that attitude is far more important than aptitude when it comes to hiring employees, for instance, or just how important great contacts are.

There were, however, two things we were absolutely sure about: 1) creating a business we would want to buy from if we were the client, and 2) being a workplace we would want to work in if we were employees.

These two things continue to shape everything we do, and like Cuban we try to make our company a genuinely fantastic place to work. From days out whitewater rafting to organizing an ice cream truck to stop by on a hot summer's day, we understand that if our staff members are happy, our clients will be happy. It's a virtuous cycle.

Employees want security, clarity, consistency, and freedom--it's up to you to give it to them and help them thrive both professionally and personally.

5. Know your business, inside out.

The best entrepreneurs I know have great instincts. They seem to know which business deals to invest in, which products will be an instant hit, or what will be the next big trend.

That said, instinct alone isn't enough to do well over the long term. No one is that lucky. So as well as having great instincts, successful entrepreneurs also know their business, their sector, and their customers. They understand exactly what is required to satisfy their customers, and crucially, what their competitors offer.

Cuban is the epitome of this principle. In his early 20s, he bought a $99 computer and taught himself how to program by reading every manual he could find. The result? A thorough understanding of the technology he was selling and the insight to make it better.

This knowledge is power. Harness it, and use it to your advantage.

6. Listen to feedback--and act on it.

While listening to customers isn't always helpful when it comes to sparking innovation, it is a must in terms of feedback for your business. Cuban once said: "Your customers can tell you the things that are broken and how they want to be made happy. Listen to them. Make them happy."

It's a simple sentiment, but one that is often overlooked. I've seen countless companies spend thousands of dollars on expensive market research when all they needed to do was look closer to home. Most customers will take the time to tell you their thoughts--be that what works well and what doesn't or what aspects of your service they like and don't like.

Your customers are one of your greatest assets, so treasure them and ask them regularly. It's amazing what you can learn when you listen--and I mean really listen--to their answers.