As the holidays approach, don't fiddle with the checkout process or offer a slew of new products. Try these testing suggestions from Offermatica's CEO instead.

The holiday season is drawing near, complete with dramatic increases in sales-- and the accompanying fear among online marketers of doing any testing that might jeopardize those increases.

Giving in to fear, however, can be risky. The testing of promotions and content during off-peak times results in significant increases in ROI. Imagine how much more you can bring in by testing during the busiest of times. Here are 10 tests:

1. Landing page merchandising
There is nothing more important on a retail landing page than how you display merchandise. What products you show, how many are displayed, the size of photographs, the quantity of copy all benefit from testing and optimization.

Test how products are grouped: Try listing best-selling items versus most-often-recommended items to see which prompts visitors to buy.

2. Percentage off versus dollar savings
Customers respond differently to promotions, depending upon how they are framed, even when the ultimate price is the same (10 percent off vs. $10 off a $100 purchase).

You can also test free shipping -- the most popular holiday promotion last season -- along with the threshold for free shipping. Does the resulting boost in sales make up for the loss in shipping fees?

Test how long you offer free shipping. The promotion matters a lot in early December, but ceases to matter later in the month. Last-minute shoppers tend to make purchases no matter the cost. At what point do you stop offering it? On December 15th? December 18th?

Divide your traffic and show visitors two offers: 90 percent get free shipping, 10 percent do not. The branch of the test receiving free shipping will most likely show increased sales over the other.

As the holiday approaches, you'll reach a point when free shipping stops having an effect, and the branches begin to converge. At that point, stop the free shipping and save yourself a bundle without sacrificing sales.

3. Encouraging customers to "act now"
Improve conversions by generating a sense of urgency among visitors. Test different scarcity messaging like "While Supplies Last" vs. "Offer expires November 31st."

4. Reflecting paid search content
Create customized landing pages for your five top-performing keywords. Make sure that the landing page content obviously relates to the search terms. You might repeat the search phrase verbatim, or reorganize your content to narrow the focus of the page.

It helps to consider the intention of visitors who arrive using those top five keywords. For brand-specific keywords, test an offer-based landing page focused on selling, as brand-specific words sometimes indicate a higher level of intent.

Category words can indicate that a visitor is in a browsing mode. They might need more trust statements and branding elements.

5. Reinforcing affiliates
Reminding customers where they came from can also increase conversion, especially if a visitor stands to gain by spending money with you.

Try showing the logo of the affiliate to those who arrive from affiliate sites.

6. Promotions in email marketing campaigns
Marketers can carry the email promotion forward onto the website, customizing it so that only the people who received the offer will see the offer, and so that they will see only the specific offer that they received in the email.

If you plan to run a free shipping promotion in an email, you might test various thresholds to see which brings optimum results. Offer A might be, "Spend $100 dollars, get free shipping," while Offer B would be, "Spend $150, get free shipping."

On the website, those who saw Offer A would see it reinforced, while those who saw Offer B would see that offer.

7. Call to action
On paid search and email campaigns, test "Learn More" or "Start Now" versus "Buy." When writing your call-to-action copy, finish the "I would like to…" sentence.

8. Gift suggestions
Test whether gift suggestions affect sales in your particular environment, beginning with your own idea of a great gift. Is it really something people want to give?

The sooner you offer what people actually want to buy and give, the better.

9. Increasing trust during checkout
Test confidence information (return policy, privacy policy, recent awards, et cetera) and security trustmarks (TrustE, VeriSign, et cetera) above the fold and in combination with each other to see if you can reduce abandonment rates.

10. Radical simplification
Cross-sells and other content may increase visitors' average order values, but there may be a downside-- superfluous content can distract customers from completing their purchases.

Lost revenue from abandoned shopping carts may exceed revenue gained from cross-selling. Test and find out!

As the holidays approach, don't rewrite the entire holiday experience by fiddling with the checkout process or offering a slew of new products. Instead, make certain assumptions about merchandising, categorization and promotions, and be willing to test them. You'll find you can improve revenue far beyond expectations.

Matthew Roche is the CEO of Offermatica, the leading campaign optimization service that helps marketers improve advertising and website performance. Read full bio.