This post originally appeared on Business Insider.  And don’t forget to download Sailthru’s 2016 Holiday Marketing Playbook for more holiday marketing trends, forecasts and best practices to help you win this season and beyond!

When it comes to long-term success in retail, turning occasional shoppers into lifetime customers is one of the most effective strategies a business can implement. And at no time is this more important than the holidays. It’s simple math: Engaging seasonal shoppers and converting them into repeat buyers provides a solid foundation for higher sales throughout the year.

Savvy companies know it’s far more cost-effective to strengthen relationships with existing customers than it is to find and acquire new ones. A recent global study by Forbes Insights and Marigold Engage by Sailthru shows companies that make retention a priority significantly increased year-over-year market share compared with those that focused on acquiring new customers.

But building those lifetime customer relationships doesn’t happen by accident. It takes a solid retention strategy and effective deployment of email, online and mobile messaging, and customer loyalty programs, especially during the holiday season. For many retailers, it’s a make-or-break moment. Sure, numbers may be up during the gift-buying rush, but if businesses fail to put retention strategies into place, those customers will disappear just as quickly as they showed up.

Luckily, those fourth-quarter shoppers present a huge opportunity for years to come — if handled correctly. Here are some suggestions for turning holiday shoppers into lifelong customers.