Starting a business can be one of the most terrifying things you’ll do in life. Having your own company can make—or ruin—you, and the risk of failure and even bankruptcy are enormous.

So why do people still do it? Because they know that they can make a difference, despite the hurdles. If you’re smart and good at what you do, you can make a lot of money and leave a lasting impression on your industry. But if you’re thinking of starting your own business, be prepared for the risks to balance out the rewards. Here’s what those who know best have to say about the business of starting a business—what to do and what not to do.

Equity champion Henry Kravis of finance firm KKR says that it’s necessary for a new company to “define [its] culture as early” as it can. He offers words of caution about going public, too, encouraging companies to only take that route when they have a really good reason. Kravis sees problems with companies whose only goal is to go public, urging more elasticity in a company’s goals. His own firm has branched out into new sectors, ensuring its health and longevity as a finance giant.

CEO and chairman of Berkshire Hathaway Warren Buffett says that Thomas Murphy, a member of the company’s board of directors, gave him the best piece of advice he’d ever received. “Never forget, Warren, you can tell a guy to go to hell tomorrow—you don’t give up the right. So just keep your mouth shut today, and see if you feel the same way tomorrow!” This piece of advice may be especially pertinent for new CEOs who are full of bright ideas and an eagerness to get things done their way. Remember, tomorrow is another day.

Richard Branson, founder and chairman of the Virgin Group, also believes in waiting for tomorrow. “My mother always taught me never to look back in regret but to move on to the next thing,” he says. Not every venture will be a resounding success, but not all of them will fail. “I have fun running all of Virgin businesses—so a setback is never a bad experience, just a learning curve,” he adds.

There’s a lot to be said for continuing to better yourself. The more you know, the more you can do, says Diane Bryant, senior VP and general manager at the Data Center Group for Intel. “There is value in expanding and rounding out your expertise and skill set,” she says. Maybe you’re a big time CEO, but there is always another way for you to grow professionally. Look for those opportunities and take advantage of them.

In the rush of starting a new business and getting yourself out there, it can be easy to get swept up in the momentum rather than realism. Reece Pacheco, founder of Shelby.tv, a technology company recently acquired by Samsung, encourages people to remember to “be human” in business. Remember that you are a person and that your staff are also people. “What makes an entrepreneur is not knowing everything about business, but rather being passionate and fearless,” he says.

Be smart, be fearless, be human—and success might be yours to claim.