Editor's note: Vote for your favorite company from among this year's 30 Under 30. Inc.com will announce the 2015 Readers' Choice winner on April 30. 

To help Inc. staffers judge the roughly 550 applicants vying for this year's 30 Under 30 list, we tapped such entrepreneurial superstars as AOL co-founder Steve Case and 30 Under 30 alum Sarah Prevette. The final list reflects their wisdom, keen gut instincts, and ability to see glimmers of future greatness.

We also asked them a few questions that we frequently hear from young entrepreneurs, and we think their answers provide a roadmap for success to just about anyone starting or growing a company. Here are their edited remarks.


What is the single most important character trait that contributes to entrepreneurial success, and why? 

Perseverance is one of the key factors to entrepreneurial success. Some of the best ideas and the most successful companies exist today because someone refused to take no for an answer. When we started AOL 30 years ago, only 3 percent of people were online, and they were online only about an hour a week. When we went public in 1992, after nearly a decade of being in business, we had fewer than 200,000 customers. But we kept at it, interest in the internet finally exploded, and a decade later, we were the leading internet company with 25 million customers and one of the most valuable businesses in the world. Perseverance isn't easy. It means pushing against currents that can be relentless. And it means constantly having to deflect the advice of people who think you should throw in the towel. But if you want to change the world, you need to be fearless and never give up.  


What do you know now that you wish you knew when you started your business? 

Strive to make fewer things with more focus on the things you make. When you start out, there is a tendency to hedge yourself--more products, so you have a better chance of finding the right product; more features, so there is a better chance of finding the killer feature; more price points, so there is more chance of engaging any customer; more ways of saying things, so people will understand. But, as you divide your focus across more things, you divide the potential of success. Instead, endure the process of whittling down your ideas to their primary elements. Focus on the few things your customer truly needs. A great MVP, or minimum viable product, favors top customer needs, very few customer wants. 


What common bit of entrepreneurial wisdom do you disagree with, and why?

Many people think that the first thing you need to do is get funding and get people rallied behind your idea. I believe you should start by getting as much traction as you can. Once you have that early traction or some indicators of success, you can go out and seek investors with more leverage. 


What was the most pivotal moment in your business, and what did you learn from it? 

When I sold my first company, Erving Wonder, to Sanctuary Group UK in 2004, we went from a small team of seven to a publicly traded company with 650 employees. I learned what it meant to lose the culture of your company and how important culture is. So no matter the size of the company, culture and your people should always be on top of the list because if you don't tell the story the story will tell itself. 


Entrepreneurs are always coming up with ideas. How do you determine which ideas are worth acting upon? 

Great ideas are built around real needs. I'm a huge advocate of human-centered design, rapid prototyping, and validating your hypothesis early on with your target market. Outside of testing your assumptions, ideas are worth acting upon only if you've got a burning passion to dedicate yourself to them. Good ideas are not enough; it takes unrelenting perseverance and hustle to execute successfully. Ridiculous enthusiasm for a validated idea plus unfair advantage (deep expertise, expansive network, industry partnerships, etc.) makes for a worthwhile venture.