Amazon.com Inc.’s marketplace sellers had a solid Thanksgiving weekend, bringing in an Internet Retailer-estimated more than $2 billion in sales from Thanksgiving Day through Cyber Monday.

Amazon says marketplace merchants, which it refers to as “small businesses and entrepreneurs,” sold nearly 140 million units globally. The retail giant declined to disclose sales figures for the five-day period beginning Thanksgiving Day, but Internet Retailer estimates that retailers and brands sold approximately $2.1 billion worth of goods on Amazon’s U.S. marketplace during the Nov. 23-27 time frame.

Digital technology provider Adobe Systems Inc. estimates U.S. shoppers spent a total of $19.62 billion online, and based on that data, that means Amazon marketplace sales accounted for approximately 10.7% of total e-commerce spending from Thanksgiving Day through Cyber Monday.

Amazon did not disclose comparable data for the 2016 Thanksgiving weekend. But technology vendor Skubana says its retail clients that sell on Amazon grew sales 19% during the five-day period compared with the same period in 2016. Skubana, which helps retailers and brands sell on marketplaces, doesn’t disclose how many clients it has, but CEO and co-founder Chad Rubin says the company is approaching 1,000 customers.

It is becoming more challenging for sellers to grow on Amazon’s marketplace, which has an estimated more than 2 million sellers and more than 300 million SKUs, and Amazon’s continues to expand the sale of its own inventory and brand names. Therefore, experts say marketplace merchants can no longer solely rely on Amazon’s traffic for growth. Sellers need to be more thorough and creative to drive sales on Amazon’s platform.

“Sellers have to be much more sophisticated in their promotions and business planning than they have been in the past,” says Jeff Cohen, director of marketing at Seller Labs, a technology provider that sells software to help merchants sell on Amazon. Strategies sellers should pay attention to this holiday season include investing in Amazon Sponsored Ads (keyword-targeted cost-per-click ads on products, headlines or listing pages), marketing outside of Amazon, refining product listing pages and getting creative with promotions. Amazon Sponsored Ads include keyword-targeted cost-per-click ads

Nomader, a retailer that sells collapsible water bottles, grew its Amazon sales from Black Friday through Cyber Monday 57% compared with a year ago, founder Bryan Sarlitt says. That growth stemmed from the retailer’s investments in Sponsored Product Ads to get in front of more targeted shoppers and stand out from the sharp increase in marketplace competition, and its “smarter and more conservative” discounting strategy, he says. Nomader increased Amazon ad spend by 69% this year compared with last year, he says.

Sarlitt wasn’t the only Amazon seller to increase spending on Amazon’s marketing campaigns, such as sponsored product listing ads, which are cost-per-click ads aimed at helping drive sales and traffic to an Amazon product detail page. Seller Labs’ Cohen says the volume of retailers advertising on Amazon has increased “significantly” year over year, based on analysis of Seller Labs’ customers. In part, that’s because Amazon now offers more ways for sellers to advertise on its marketplace.

But most retailers can’t boost sales simply by increasing their ad spending, Cohen says. If sellers didn’t see a bump in sales or volume from their Amazon marketing campaigns over Thanksgiving weekend, there’s still time to refine the campaigns before Christmas.

Sellers should analyze the number of sessions (unique visitors to product detail pages) and the number of orders, Cohen says. If traffic to product detail pages is not increasing as a result of Amazon-sponsored ads, then merchants should tweak the keywords they’re using.

“Sellers make the mistake of wanting a lot of impressions, so they add a lot of keywords,” Cohen says. For example, a merchant selling an apple slicer may be tempted to add the keyword “kitchen” on the listing page so that her product comes up in a broad range of search results. But the number of impressions does not effectively lead to sales, and therefore Cohen advises sellers to be specific and accurate with keywords, such as “apple cutter” in this example.

If sellers find that customers clicked on the page, but didn’t convert, that means the content on their listing pages is not convincing customers that their product does what the keywords are saying. Therefore, Amazon sellers should update their product titles and descriptions with accurate and specific keywords so when customers click on their product pages, they’re more likely to purchase, and sellers are less likely to waste ad spend, Cohen says.

Here are other strategies marketplace experts recommend:

• Advertise outside of Amazon. Nomader sent an email promotion over the weekend to its website subscribers that linked directly to its Amazon listings. While Amazon has not confirmed this, “based on our testing and discussions with other sellers, it seems that Amazon’s algorithm puts a high value on outside traffic and will reward those listings accordingly with higher keyword ranking if the traffic converts well,” Sarlitt says. Other sellers have marketing campaigns on social networks like Facebook that link to Amazon listings.
• Refine product pages with compelling content. “We live in a visual world, so five to seven images are necessary to win on Amazon,” Rubin says. Compelling content also includes good product descriptions and titles.
• Be smart with promotions. “Customers over the Cyber 5 weekend are looking for massive deals,” Cohen says. “If your product had a superficial deal, then you didn’t give a large incentive to buy. 10% off isn’t going to get someone super excited. Sellers have to be looking for a halo effect.” That could mean that sellers are OK losing profit or breaking even over the holiday weekend, with the goal in mind to boost brand awareness so much so that it can still get sales on the product as the price increases.