Happy customers are an incredible asset to any business. From testimonials to referrals to great feedback, they're the ones who can help you improve your product and even grow sales. But too many entrepreneurs forget to do one simple thing: listen.

Last week, 10 founders weighed in on questions to ask your least happy customers; this week, 12 more entrepreneurs from YEC shared the most effective questions to ask customers on the opposite end of the spectrum.

Their best answers are below.

1. How do you describe us to your friends?

Ask your happy customers to use three words to describe your product and company. These can often sound like weird poetry without a strong connection between the words, but more often than not you'll find that some key words keep popping up over and over. That is so exciting to me, and is just pure validation that we're onto something huge.--Rob Fulton, Exponential Black

2. What frustrates you most about this industry?

Ask what frustrates them most about your industry--this does something special. You find out a pain or frustration that you can eliminate for them. They may normally just share that you are fast, friendly or high quality, but may never share that they really hate the lack of integrity in your industry. Also find out what they love about you; their negative hot buttons are just good to know to avoid hitting.--Matt Shoup, MattShoup.com

3. Will you write us a testimonial?

Ask every happy customer for a testimonial and put it live on your site. Get them to write it out as long as they can. Show your other customers. Show the world what people are saying about you and your business: It will help you grow like nothing else.--John Rampton, Host

4. Can we ask you for help in the future if we need it?

We used to ask happy customers to post about us and tell their friends about their great experience. We finally realized that asking for a favor runs the risk of turning a great feeling into a transactional one. Now we fight to leave the positive relationship open, as you would any friendship. Our customers know that we don't want to waste their time. But they'll be there for us later if we need it.--Aaron Schwartz, Modify Watches

5. Will you join our customer advocacy council?

Get your happiest and most engaged customers to help give feedback on your roadmap, marketing and support by inviting them to join a small advocacy council. Getting direct feedback channels to your customer is invaluable, and they will love being involved in shaping your company's future.--Trevor Sumner, LocalVox

6. Can we run some new ideas by you?

The people that love your brand the most tend to "get you." Every brand has an intended message and audience, and the people who love your brand tend to represent that target quite well. Invite your fans to comment and collaborate on new features or ideas. Open lines of communication and ask if those who love your product as it is will love it even more as you improve.--Brian Honigman, BrianHonigman.com

7. What do you like about our competitors?

Ask if they've ever thought about leaving your company/service for one of the other options in the market. And if so, why? Find out what they were offering that you weren't, and why it wasn't enough to make them actually leave.--Anthony Saladino, Kitchen Cabinet Kings

8. What will you remember most from our experience working together?

This is a useful question to ask because it provides insight into the aspects of our interaction that were most important to them, which we can then emphasize in future client interactions.--Jyot Singh, RTS Labs

9. Would you recommend this site to your friends or family?

This questions sums up the entire experience of your site. Have you created a product that customers love so much that they are willing to refer it to their friends? Have you solved their pain point and have you created a great user experience? That said, be careful when you ask this question--people tend to say "yes" more often than they say "no"--they don't want to hurt your feelings.--Joseph DiTomaso, AllTheRooms

10. Will you join our loyalty program?

One of the best ways to reward your happiest customers is to give them the chance to enjoy future business at a discounted price. It helps the business, too, by de-risking future sales. By asking your happiest customers whether they'll consider recurring products or services from your company, you'll also better understand their purchasing habits and predict their future needs.--Doreen Bloch, Poshly Inc.

11. What is one thing we could build next that you pay extra for?

Roughly a million times more cost effective and efficient than traditional market research: Lean on your happy customers to help build your product roadmap. Ask one simple question: What is one product or product feature that you would be willing to pay extra for?--Joel Holland, Video Blocks

12. Would you like to be a part of our team?

To get your most satisfied customers further invested in your brand, have them support you as advocates and promoters. Offer contests or events where you ask them to share how much they love your product on social media outlets like Facebook, Twitter and Instagram. That way, they feel like they are contributing to the team while also helping boost brand awareness.--Firas Kittaneh, Amerisleep