3. Stocking the store with surprising finds

To keep customers shopping, retailers must strive to design their stores in a way that confronts shoppers with items that pique their interest and keep them browsing.

"One of the things that really keeps people in stores longer are new and unexpected discoveries," Sturgess said. "This is what transforms shopping into an experience and not just a transaction."

Sturgess highlights stores like Urban Outfitters and Costco that are packed with a range of products intermingled with one another. For example, in Urban Outfitters, one might be browsing for pants one minute only to stumble upon a stack of new books.

Along the same lines, Beemer emphasizes the importance of signs placed throughout the store. Adding signs that advertise new seasonal products or special deals can be an effective way to direct consumers to other sections of the store.

"Everything within a good store signage program is intended to keep the customer in the store longer and to spend more money," he said.

4. Improving customer service

As useful as each of the above steps may be to entice customers, none compares to the importance of great customer service.

"The No. 1 thing that keeps a customer in the store longer is having a representative to help them who is friendly and knowledgeable," Beemer said.

However, the bar for quality customer service is arguably higher now than it's ever been. It's no longer enough for representatives to know the store's selection or the basic specifications of a product; consumers can find out much of that information on their own online or on the smartphones in their pockets. Sales representatives today must be experts on the products they sell and even on the industry as a whole, and should be able to provide insight that the shopper wouldn't be able to find elsewhere.

As an example, Beemer and others point to Apple, which has a special Genius Bar that features experts who handle tech support and offer opinions on your gadget needs as well.

"If the customer feels the representative is trustworthy and knowledgeable, they are more likely to ask for their opinion or advice and to stay in the store longer. If not, they may feel their time is wasted," Beemer said.

5. Making the most of customer downtime

As much as retailers may struggle to keep consumers in stores longer, they often seem to overlook the instances when customers have no choice but to hang around, whether it's waiting for a prescription to be filled at a drugstore or for a pair of pants to be hemmed.

"There is an opportunity to engage customers while they wait for service and leverage that downtime, but that often seems to go overlooked," Sturgess said.

She recommends display videos in checkout lines and other waiting areas that show how to use a product or perhaps highlight community programs the store is involved with. Likewise, representatives might take these opportunities to inform waiting customers about other promotions.

"If the customer doesn't want to participate in this, that's fine, but at least give them the option to do so," she said.

6. Catching you on your way out

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Once customers decide to leave the store, retailers have one last opportunity to keep them there a little while longer.

Some retailers, according to Beemer, have begun to offer coupons and discounts at the cash register along with the receipt, to encourage the customer to turn around and pick up an extra item or two.

"Stores won't do this as much ahead of time because it's not as effective at getting you to buy more . . . but when the salesperson gives you a 20% off coupon with your receipt, it might get you to go back and stay a little longer," Beemer said.

This article was reported by Seth Fiegerman for MainStreet.