Online, customers often abandon their shopping carts. Here are some tips to help you walk more of them to the finish (checkout) line. (Sarah L. Voisin/The Washington Post)

The average American is expected to complete 44.4 percent of their holiday shopping online this season, and the National Retail Federation predicts online sales will rise around 8 to 10 percent over last holiday season.

However, as quickly as online shopping is growing, it could be growing even faster. Many small business owners who operate an online storefront may be all too familiar with the abandoned cart alerts that trigger when a shopper fails to complete their checkout. But did you know that a whopping four trillion dollars worth of merchandise will be abandoned in online shopping carts this year?

Those alerts tell you there’s a problem, but what’s the solution? How will you take action to maximize checkout during the holiday shopping season?

While cart abandonment is a natural occurrence in online shopping, there are several steps you can take to at least lower your abandonment rate. In fact, estimates based on the real market impact of existing tools suggests that 63 percent (or $2.52 trillion) of that $4 trillion in unrealized revenue is recoverable.

Here are some tips to help you capture more of those sales this season and beyond:

Deliver online, in-store and mobile experiences

Some potential customers that leave your website with items still in their cart probably plan to come back to your site or your physical store location (if available) to complete their purchase. Naturally, having several opportunities for shoppers to find their way back to you online, in store or on a mobile device increases the chances that they will actually complete the sale.

Business with an online and brick-and-mortar business are wise to mine real-time cart abandonment data to make decisions about email or mobile retargeting campaigns (discussed more below), in-store placement and in-store promotional offers. Online-only businesses must ensure they are offering mobile-friendly sites that are attractive and intuitive to navigate.

Related: Common holiday marketing mistakes to avoid

Additionally, 79.5 million Americans are expected to make a purchase via a mobile device this year. Mobile is no longer an option, but instead a necessity as a way to be available for your customers to buy wherever and whenever shopping-decision inspiration may strike them.

Streamline your online and mobile checkout process

The number of steps in a checkout process is directly correlated with cart abandonment – in other words, the fewer steps, the better the checkout rate. Ask for as little new information as you need and introduce time-saving options like stored payment information. Also, test your checkout process and look for time-saving improvements.

Ask a friend or family member to test drive your checkout to see where any hiccups may occur, and to help you improve the experience on your Web and mobile sites. Make sure the “Add to Cart” and “Checkout” buttons are easily noticeable at both the top and bottom of your pages. Providing a “steps remaining” visual chart which tracks a customer’s progress through the checkout process can also help situate customers, reducing anxiety and frustration and improving checkout rates.

And remember, it’s a best practice to display the item description, price, shipping cost and tax right when a shopper adds a product to cart. In addition to extra steps in checkout, unexpected charges can make a customer hesitate to spend those hard-earned dollars.

Offer multiple payment types, including credit

Consumers want the freedom to choose different payment options when completing purchases, including credit cards, debit cards and digital wallets. Moreover, offering financial flexibility via credit promotions is a powerful way to increase the likelihood of a completed sale. This could include extending a promo-period interest-free credit to shoppers.

Conduct retargeting campaigns

Don’t be scared to follow up with shoppers who abandon carts. Targeted emails from businesses following up on abandoned carts have a 46 percent open rate, a 35 percent click-through rate, and can lead to an online purchase.

Be careful not to over-rely on email for retargeting though, as you want to cut through the noise of spammy emails. There are several other retargeting approaches you can try besides email, such as “display retargeting,” which are ads for your company that pop up for people who have previously visited your site and that appear while they browse the Internet.

Go ahead, put these tips to the test and see how they work for you. Good luck in your holiday selling season!

Dan Leberman is vice president and general manager of North America SMB Core and Online Business at digital payments company PayPal.