Without this one thing, the whole campaign falls apart. Unfortunately, it’s also often the most overlooked part of a marketing effort. It’s not the graphics, or the words, or the size of the brochure that matters the most. It’s not even what you’re offering or the price.

The key to success (in fact up to 40% of your return) is… the list.

Teenagers won’t buy your denture cream (no matter how slickly produced your ad is).

Since the list is so important, treat it carefully. Don’t look for the cheapest list, look for the list of people that best matches your target audience. It’s tempting to get compiled lists (like those from InfoUSA) because they’re inexpensive. But there’s a hidden cost – bad data. Purchasers have reported up to 27% error rate (a clean list has an error rate of 2-3%).

Good B to B lists can cost up to $275 per thousand names, so choose wisely. Look for lists of purchasers, attendees, or subscribers. Ask for a data card. This is the list’s biography. It shows when the list was last updated, the pricing, the demographics of the people on the list (age, income for consumers or titles, industries for businesses), and the different selections available. A selection is a subset of the list, for instance, only people in manufacturing businesses or only people with incomes over $50,000.

Where do you find lists?

Call a list broker. (contact me and I’ll give you the name of a good one). List brokers have access to thousands of data cards on thousands of lists. Tell him (or her) your target audience, your product, and your offer (what you’re selling and for how much). Also, send a sample of your brochure or a link to the Web page for the product.

Check direct marketing publications. Direct magazine or DM News. Both are free, and keep their subscribers up to date on new lists.

Contact trade publications in your industry. Many will rent the names of their subscribers.

Build your own. Create a newsletter, e-book, or free offer, and build a list of people who want to hear from you.