By Dean Rieck
One of the primary advantages of using direct mail is your ability to divide and conquer. Your letter delivers a personal message and makes an offer. Your brochure demonstrates features and dramatizes benefits. Your order form calls for action and eases response. 
Each piece performs a specific function and, because each is dedicated to that function, does a better job than a mailer attempting to do everything simultaneously. With that in mind, consider testing an appropriate insert or involvement device that can boost response enough to offset the additional cost. Here are eight ideas:
1. Encourage involvement with a quiz or checklist. Is your offer relevant to your prospect? You can prove that it is by including a simple quiz: “Do you qualify for our 80 percent discount on life insurance? Take this quiz and find out.” Or a checklist: “Here are 25 ways our investment course can turn you into a millionaire in 10 years.” 
2. Make your offer tangible with a check or coupon. If you’re offering $25.00 off, enclose a coupon or simulated check worth $25.00 and instructions for returning it with an order. If you can, offer a real check that provides an instant reward or even activates a service when cashed. A check can be personalized and show through an envelope window. 
3. Dramatize your offer with stamps or stickers. If you have several offers, configurations, or options, you can print each on a stamp and ask the recipient to affix one to the order form. Stamps and stickers are highly involving and make it clear that some action is required. 
4. Answer objections or highlight a benefit with a lift letter. The lift letter is the dean of all inserts. It is usually a short message signed by someone of higher authority than the letter signer. It presents a second point of view, meets objections, adds credibility, highlights benefits, etc. 
5. Increase credibility with a testimonial insert. Testimonials often work best when you print them as a stand-alone piece, which increases the “bandwagon” effect. You can also have a benefit headline to introduce them, such as “Over 3 million satisfied customers agree, a Wahoo Widget lasts so long, it’s the last widget you’ll ever have to buy.” 
6. Prove your superiority with a sample. Let’s say you’re selling a coat or jacket to outdoor enthusiasts. You claim it will withstand all manner of torture because it’s waterproof, fireproof, rip proof, and stain proof. Enclose a one-inch square of the fabric that is attached to a small card with instructions for testing the fabric. That way, your prospect can see firsthand that your product is everything you say it is. 
7. Emphasize exclusivity with a membership card. People like to belong. If you can structure your offer as joining a club or organization, you can send a membership card printed on plastic or heavy paper. You can even personalize it, provide contact information and list benefits. 
8. Reinforce your guarantee with a merchandise return label. It’s one thing to say a dissatisfied customer can return a product. It’s another to actually provide a prepaid return label in advance. It shows how confident you are in your product and lowers perceived risk. One way to do this is to combine a label with a lift note that explains the return process and how there’s no risk or obligation for responding. 

—Source: Dean Rieck is a leading direct mail copywriter. For more copywriting and selling tips, sign up for Dean’s FREE direct response newsletter and get a free report, 99 Easy Ways to Boost Your Direct Mail Response.