U.S. online holiday sales will increase 12.2% this season to $129 billion from $115 billion in 2016, according to a forecast from Forrester Research Inc.

More consumers will shop online this season, with the total number of web shoppers in the United States estimated at 196 million, up 3% compared with last year, says Forrester, which defines the holiday season as Nov. 1-Dec. 31.

Driving the double-digit increase in online shopping is Forrester’s expectation that shoppers will spend 8% more online this season, averaging $689, according to the Forrester report, authored by Fiona Swerdlow, vice president of research. Projections are based on a Forrester and Bizrate Insights survey of 3,324 U.S. shoppers in June and July.

Forrester cites strong consumer confidence and solid economic conditions as the foundation for what should be healthy online retail sales growth. Store sales are expected to be flat with 0.3% growth to $549 billion, Forrester says.

A continuing trend for 2017 will be consumers’ tendency to procrastinate. “In 2016, late-holiday-season shopping increased against previous years, with marked growth in the latter half of December,” Forrester says. “Since online last-minute purchases at this point generally do not arrive in time for the Christmas holiday, retailers with click-and-collect [buy online, pick up in store] web functionality, quick shipping solutions or promotional incentives that direct foot traffic to stores can capitalize on shoppers’ final purchases.”

The period often called Cyber Week, which kicks off on the Monday after Thanksgiving (Nov. 27 this year), will be a big online shopping period, Forrester says.

“43% of U.S. holiday shoppers tell us that Cyber Week will be their ‘biggest online shopping period of the year,’ a record high since 2011,” Forrester says. “By now, retailers have much of their marketing plans in place, but it’s worth reviewing those plans to see how they speak to ever-connected customers. Review your holiday marketing plans to ensure they hew to the hallmarks of post-digital marketing.”

E-retailers can employ several marketing tactics to boost their sales performance during this critical week. Forrester offers these insights:

• 64% of online shoppers agree or somewhat agree that they like seeing recommended or suggested products from retailers, according to Salesforce.com Inc. Forrester suggests retailers work with their ad technology and media buying partners to avoid wasting ad spend by spamming customers with ads for products they’ve already bought.
• 28% of U.S. holiday shoppers want to hear about deals during the holiday shopping season, and 11% said offers prompt them to buy even if they hadn’t planned to do so.
• 79% of online shoppers strongly or somewhat agree that they like receiving complementary offers or promotions based on their purchase history.
• Retailers should align their social tools and technology to the customer life cycle. Social ads and influencers help discovery. Online social tools work when customers are in the “explore” and “buy” phases, and communities and chat help when customers have questions about the product.
• Be timely when responding to shoppers. 68% of online consumers expect brands to answer within a day, and 26% expect to hear back in less than two hours.

Mobile performance also matters to online shoppers. Mobile visits to retail sites have risen 66% since 2015 and as of the second quarter of 2017 account for 54% of web visits for large retail websites, up from 33% a year ago, according to Adobe Digital Insights. Digital measurement firm comScore Inc. found that U.S. holiday retail spending in 2016 via smartphones and tablets grew 44% year over year.

Still, customers find mobile checkout onerous, Forrester says. “During the holiday rush, retailers need to get mobile checkout right or risk sales during a period when time-starved customers may be more inclined than otherwise to buy on their smartphone,” Swerdlow writes. E-retailers can address mobile concerns by:

• Streamlining checkout to avoid asking customers to enter information they’ve already added earlier in the process.
• Eliminating stumbling blocks, such as content and text that are too small to be useful and layouts that don’t work on small screens, such as multiple columns.
• Promoting digital wallets that customers use. Know which digital wallets your customers want to use and be selective in what you offer. And when you ask for numeric payment information, proactively flip to the numeric keyboard.
• Measuring more meaningful indicators, such as completed mobile checkouts, speed and load times, and how long it takes the customer to complete the checkout.

Smoothing the mobile checkout also means ensuring a retail site is optimized for speed. Forrester says savvy retailers will:

• Turn off dynamic content. Assess all dynamic content, isolate and turn off those content elements that come from suspicious sources that won’t handle heavy load, and delay load so the rest of the experience doesn’t suffer (e.g., campaign pixels).
• Limit page weight. Set a performance page weight “budget,” start with the low-hanging fruit of limiting image size and embed engineering solutions (such as Google AMP, Facebook Instant Articles, or HTTP/2) into your design and development standards for future iterations.