Starting a business not only takes risk, but the ability to adapt. This is especially true for first-time entrepreneurs, as many elements of starting up--from hiring to planning to leadership--require a learn-as-you-go approach.

But which lessons stand the test of growth and become more like personal mantras? To find out, we asked 15 successful entrepreneurs share their No. 1 piece of leadership advice for first-time startup founders. Their best answers are below.

1. Early hires will make or break your company.

The first couple hires you make for your company are super important. They will set your company culture and create the foundation on which your entire organization will be based. You cannot build a solid business on a shaky foundation. Find great people and surround yourself with them.--Arian Radmand, CoachUp

2. Service-based leadership leads to the most fulfillment.

Owning a service company that deals with people's stories is incredibly personal. Serving those people continues to teach me what I'm made of, pushes me to be my best and creates emotional reward beyond what I imagined possible. Giving people the tough love they need and challenging myself to hear tough feedback leads to humility and joy. A focus on service melts away other challenges.--Corey Blake, Round Table Companies

3. What you focus on expands.

I've learned that what you focus on is what you create. It really works. When you focus on what you intend to create, and you focus on it intently, you can make it into a reality. This means focusing on only that which serves you and your mission and letting go of all the things that hold you back. Focus on the positive and moving toward your goal, and not on the negative and any struggles.--Andrew Thomas, SkyBell Technologies, Inc.

4. Keep balance in all things.

As a business owner, there are many things you have to learn to balance, such as work and personal life, existing clients and searching for new clients, realistic marketing goals and your marketing budget; the list is endless. If you lean towards one side or the other, you'll be losing out in some aspect. -Stanley Meytin, True Film Production

5. Lead with analytics.

I've learned to make business decisions based on thoughtful consideration and analysis, rather than basing them on emotions. A corollary to that is to not be afraid to make changes and adjustments along the way.--David Ehrenberg, Early Growth Financial Services

6. Repeatedly validate your product with consumers.

Your friends, family, partners and investors will either give you the support you crave, or be naysayers whose opinions you ignore. The real opinion that matters is that of consumers. At every stage of developing and bringing your product to market, you should always validate it with consumers and make sure it's something that solves a problem and that people want to buy.--Jared Brown, Hubstaff

7. Don't get distracted.

Often when people start companies, they come across many great ideas and decide to start multiple businesses at the same time in order to experiment and see what works best. The problem though is that if you get distracted with so many creative ideas, it will be hard to build multiple great businesses. This is why it's best to focus on one core business at a time.--Randy Rayess, VenturePact

8. Balance between a clear plan and unplanned opportunities.

Strike a balance between having a clear plan to hit your goals and identifying new opportunities. Do so by making time to assess new opportunities and being open to new paths that may serendipitously come your way from being clear on the direction you're heading.--Lauren Perkins, Perks Consulting

9. Set bigger goals.

I started out with goals I thought would take several years to achieve, but hit them on the nose by the end of each year. I've learned that with a cohesive vision and goals, as a team we can achieve great things, even when there are losses. Now we set bigger, more audacious goals along with interim benchmarks. With my team dreaming bigger, we stay open to opportunities that come our way.--Kayla Wagner, Revel Interactive

10. Be comfortable with constant change.

A business plan is valuable to clarify your idea and help you get funding, but with innovative business models, a lot of rules are still being written. If you don't know how to write a business plan, that's OK as long you have a product or service and a market. You might not have everything figured out, but you'll need to learn to live with that. Be open to change and constant testing.--Alfredo Atanacio, Uassist.ME

11. Always trust your gut.

If my gut tells me not to hire, then I won't hire the person (took three wrong hires before I learned). If my gut tells me to call and confirm a meeting although it is in the calendar, I do (took about two failed flights and several train rides to learn this one). If my gut tells me to wear my blue dress, then I do (the client's favorite color is blue). Go with your gut!--Tamara Nall, The Leading Niche

12. You don't have to have all the answers.

Building a business is both fun and extremely difficult. Every day presents a new opportunity and a new challenge. I almost burned out before realizing one simple truth: Entrepreneurs don't have to have all the answers. Sharing responsibility with your team not only lifts a great burden, but also leads to greater results. You hired great people for a reason--lean on them!--Joel Holland, Video Blocks

13. It's about the big picture.

Always think about the bigger picture--not your personal gain. By making sure your company is successful and by rewarding key contributors, you create far more value than by thinking too much about yourself.--Philippe Clavel, Rabbit

14. Everyone responds differently to authority.

You have to realize everyone responds differently to authority. Some people need you on their backs, some people need constant positive reinforcement and others do best with minimal feedback. Once you understand the people around you and what drives them, it allows you to manage them more effectively.--Jayna Cooke, EVENTup

15. People are everything.

When choosing your co-founders, investors, employees and partners, remember that people are everything. Fit goes both ways, so make the effort to understand yourself, too. Given the importance of choosing the right people, I recommend creating a framework for evaluating potential partners and employees. Create a hypothesis and revisit it often to see if things played out as you predicted.--Vivek Sharma, Movable Ink