Having the right sales piece is crucial to the success of your direct mail campaign. And one of the most critical aspects of any sales piece is the offer, or call to action. This is the part of the copy that lets readers know what you want them to do and what they’ll get for doing it.

The call to action needs to be dynamic enough to get past readers’ natural inertia and inspire them to do something. It has to have the motivational power to convert readers into buyers.

The copy leading up to the call of action needs to do its job as well, laying the groundwork for why readers need your product or service, explaining why what you offer is the best quality and why giving your company a try is the best thing they can do to fulfill their personal goals.

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But it's your call to action that will put people over the top. It should describe all the wonderful things they will get if they respond, and instruct them on exactly what they have to do to take advantage of it.

Sadly, this is where I've seen so many sales pieces fizzle out. The call to action isn’t strong enough or clear enough to clinch the sale, which means you could be wasting a ton of money and missing out on the sales you need to build your business.

To help you avoid a serious misstep like that, here are my top five elements of an irresistible call to action.

1. Make sure you actually have a call to action

This element is perhaps the most important: you have to make sure there actually is some kind of offer and call to action in the piece.

We may think we’re so fascinating that all we have to do is introduce ourselves, and folks will come running, begging us to tell them more. But it doesn’t work that way. People will not take the time to figure out on their own what you want them to do.

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If you have a great new diet formula, don’t think it’s enough to introduce your product, say why it’s better than anything out there, have great testimonials, and just put your phone number. You have to tell people how to order, what they’ll get, and that they have to do it right away. Otherwise the chances that they will call are very slim.

In addition to the big call to action at the end of the piece, it doesn’t hurt to put brief reminders on every page, like “Order now” with the phone number.

2. Give clear instructions with limited options

You may have 26 products that you love, and all kinds of ordering combinations and programs available for customers to choose from, but readers will not want to plow through all that. And if you give them too many choices they may go into confusion about what’s their best option, and decide to end the anxiety by putting the piece down with the intention of coming back to it later when they have the time to sort everything through. That breaks the force of the sales piece, and the likelihood is they’ll never pick up the piece again – except to throw it away!

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Marketing research shows that prospects buy more when their choices are limited. So have just one or two product offers to choose from, and give very simple ordering instructions: “Call, Order on line, or Mail/fax the attached order form.”

Make sure you always include a simple offer with a clear call to action, and use strong action words: Buy, Call, Act Now! This will motivate prospects to respond.

3. Present a time limit

Even if we like a product, and think we might order, the tendency is to think, “I’ll do it later.” And then later never comes. You can help overcome that reluctance to pull the trigger by making your offer time sensitive. Prospects must respond by a certain date or the offer will be void, or they will miss out on some add-on bonus. A variant of this is to say that quantities are limited and it’s first-come, first served.

Add a sense of urgency to your call to action, and it will get a better response.

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I should mention that another reason for adding a time limit is that you want your orders to come in quickly. You don’t want them trickling in over an extended period of time. This is especially important if you want to determine how successful a piece is. You’d like to know that after a reasonable period of time – say, three weeks – you’ll have a good idea of how many orders you’re getting. If orders keep coming in indefinitely, you’ll be waiting forever to get the statistics you need.

4. Offer a bonus

A powerful offer is boosted by the addition of a bonus item. If prospects order from this offer they will receive a gift, like a free report, a CD, a coaching session – whatever you feel will add value in the eyes of your prospects.

A bonus tied to a time limit can be especially effective. Make it clear that the bonus will only be available for a limited time, or while supplies last.

In some cases you can make the bonus sound so attractive that people will order the product just to get the bonus!

5. Appropriate to your purpose

Finally, the bonus that works best for you is the one that is most appropriate to the aim and audience of the sales piece. Ask yourself what you’re trying to accomplish, and design your offer around that goal.

For example, if you’re sending out an introductory offer to a list of new prospects, your primary goal may just be to get them to make that first order so they can get familiar with your product and you can get their contact information. In that case, a low-priced introductory offer might meet your purposes the best. If you have some kind of subscription service, you might make a $1 offer, just to get contact information, and then put buyers on an autobill program that they can cancel at any time (all of this must be clearly spelled out in the description of the offer).

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On the other hand, let’s say that you’re sending a backend piece to existing customers, trying to upsell them to a more expensive package. In that case, you would probably want to go with a higher-priced offer.

With any offer, it always helps to stress that prospects can order with “No Risk.” If you have a guarantee of some kind, or prospects can cancel at any time, clearly spell this out. People are more likely to go ahead and order if they feel comfortable that they have some protection.

Related: The 5 Key Elements of a Great Direct Mail Sales Piece