3 Simple Ways to Keep Your Customers Happy The star of the Style Network's 'Resale Royalty' offers valuable lessons in customer retention.

How do you turn customers into repeat customers? Sue McCarthy of Resale Royalty, a new Style Network reality show about a thriving St. Louis secondhand clothing store, says the secret is simple.

"Always do what's right -- for your customers, your suppliers and yourself," says McCarthy. "If you operate with integrity, you keep everyone coming back."

As the owner of Women's Closet Exchange in St. Louis, McCarthy sells designer labels such as Chanel and Louis Vuitton to thousands of clients as well as to celebrity stylists. In business since 1984, she built her store into one of America's most successful resale operations. She offers these three tips entrepreneurs can use to encourage repeat business.

1. Treat your suppliers like partners.
When you value and appreciate your suppliers, McCarthy says they will feel vested in your success and will often offer you the best merchandise or services at the best prices. As a result, customers will find you to be a reliable source of good products and services.

In the resale business, McCarthy's suppliers are the women who sell her their clothing and accessories. She must get them to agree to sell their items at a price at which she can make a profit. While she initially offers a lower price, McCarthy encourages suppliers to negotiate. If they offer a price slightly higher than she had in mind, she won't necessarily walk away from the sale. Instead she considers the value of a long-term relationship with them.

"If the difference is something I can live with, I'll let them win the negotiation," says McCarthy. "When they leave with a smile on their face, they come back."

Related: 6 Ways to Build Customer Loyalty

2. Adhere to industry ethics.
McCarthy is vice president of the National Association of Resale Professionals, an organization that provides educational and professional development resources for owners of resale stores. Members adhere to a strict code of ethics, especially around the topic of authenticity.

Customers who shop at McCarthy's store are offered a 100% authenticity guarantee on their purchase. All of the designer merchandise has undergone a rigorous validation process that includes checking details, such as stitching, fonts and serial numbers. Shoppers are offered an unconditional 100% refund on any item that can be proved to be a fake.

"Our reputation depends on honesty," says McCarthy.

She says her store's involvement in setting industry standards has built customer trust. She suggests that entrepreneurs join organizations that help set guidelines and standards for their industries, and then advertise the affiliation through signage or marketing materials.

3. Empower your staff.
McCarthy gives her salespeople the authority to adjust prices without getting her approval.
"Time is very valuable," she says.

Customers who ask for a discount and suppliers who want more money for their items can deal directly with employees and don't have to wait for McCarthy's approval. "Make it simple for people to do business with you," says McCarthy.

Related: How to Turn Customers into Brand Ambassadors