Understanding how to use the sales funnel successfully—the top in building awareness, the middle to create consideration, and the bottom to convert prospects into customers—is critical to business grow. But once you do gain a customer, your job has only just begun.

Every customer you currently have must be shown how much you appreciate them and their business, to build their engagement and loyalty, and so they remain your customer. For one thing, existing customers who spread great word of mouth about you provide terrific “free” advertising for your company. And, according to Forbes, if you can increase retention by just 5 percent, you can increase your profitability by 75 percent as you gain additional and more profitable jobs.

Let’s examine a few best practices in providing recognition and feedback to your existing customers to increase their loyalty and profitability.

Recognize preferred customers. It shouldn’t be hard to know who your most profitable customers are; a simple glance at your accounting program should tell you. But perhaps even more important is that preferred customers are much more likely to give you additional business in the future and refer you to others. You’ll want to go out of your way to make these customers feel very special indeed.

Perhaps the easiest and least expensive way to start is to simply write a hand-written note of thanks for their business. They’ll feel appreciated, and recognize it as a personal, from-the-heart gesture. You could also provide discounts on their next job, or offer Starbucks gift cards during holiday season. If you work in an area where there’s a major league sports team, consider offering free tickets to your very best customers.

Check out what other printing companies (or those with substantial printing services) are doing, even those companies that are very large. For example, Office Depot and its subsidiary OfficeMax offer a range of perks to loyal customers, and it’s a pretty good model.

Referrals: a two-way street. Your best customers may not be the most lucrative in their own right, but can be your biggest fans. Consider including in your preferred customer program those customers who refer you to others, or favor you with good reviews on Yelp and other social platforms.

And consider doing some of your own referrals. Refer other individuals or businesses to your commercial customers and make sure they’re aware of the referrals. That won’t cost you a penny, but can be extremely lucrative to (and appreciated by) your loyal customer.

Feedback and insights. Reconsider how you think about your current customers. They don’t represent merely financial transactions, but should be thought of as true partners, where their success is your own.

You are the printing expert, and have tremendous insight around topics your current customers may not be aware of. As part of your marketing content effort, invest in market research that provides intelligence about printing best practices, cost savings ideas, direct mail tips and tricks, the human impact of certain ink colors that can improve the success of a flyer or mailer, U.S. Postal Service discount programs for mass mailings, details about other customers’ successful print campaigns, untapped capabilities of variable inkjet printing, and so on.

And if a customer offers helpful feedback to you, such as suggestions on purchasing, technology, or operations, and you adopt that feedback, make sure you let them know you’ve done so and are appreciative. Your customers in turn will know you value their suggestions and that you’re invested in each other’s success.

Here’s one essential statistic to remember: 80 percent of your future revenue will come from merely 20 percent of your current customers. As soon as you sign up any new customer, retention should be uppermost in your mind.

Christopher Hosford is editor at large for Target Marketing. Former editor-in-chief of Nielsen’s Sales & Marketing Management magazine, he covers all aspects of sales, marketing, and cutting-edge marketing technologies.