Your success depends on your mailing lists. According to late, great direct marketer Ed Mayer, the success of every direct marketing campaign hinges 40% on mailing lists, 40% on offer and 20% on everything else. In other words, pick bad mailing lists and you will certainly fail. Choose good ones and you are on the road to success.

So how can you find good lists for your business? Here are four simple rules to follow on your quest for better mailing lists:

Rule No. 1: Use a list broker

List brokers spend all day, every day thinking about mailing lists. Their raison d'etre is to find successful mailing lists for clients like you. Many have decades of experience in your industry and can tell you from memory the best lists and those to avoid. In addition to helping you avoid costly mistakes, list brokers have access to powerful research tools to help them formulate targeted recommendations. And best of all, their services won't cost you a penny. That's because they are paid a commission from the list owner. So buying a mailing list through a list broker won't cost you any more than buying it directly. Paying for list broker services is the best money you will never spend.

Rule No. 2: Educate yourself

You are now working with a list broker, so you can sit back and relax, right? Wrong. You know your business better than your list broker ever will. To get the best results, you must work in partnership with your broker. To be a good partner, you need to educate yourself on the spectrum of relevant mailing lists and important details such as audience makeup, counts, pricing, selectivity, usage and ordering restrictions.

Your list broker will certainly help you, too. They realize an educated customer is a good customer. Some leading list brokers have developed systems that enable clients to participate in the research process by providing online access to mailing list information and list recommendations through their Web sites.

Rule No. 3: Learn from your results

Before you mail, be sure to have the controls in place to measure the results of your campaign. This is often accomplished by assigning a unique key code for each mailing list. Responses are attributed to the appropriate key code as they arrive. When your campaign is complete, be sure to spend time analyzing the results. Determine which mailing lists worked and which ones failed. Why did some fail while others succeeded? This new knowledge will help you improve the results of your next campaign.

Rule No. 4: Share your results with your list broker

Sometimes the broker/mailer relationship can be dysfunctional, with brokers not sharing list information and mailers not sharing their results. But results would improve if each were more transparent with their information. List brokers cannot be expected to make good recommendations without understanding how well their past recommendations worked for you. You will get the best service from your broker when you treat them as a trusted adviser and a partner in your success.

Follow these four simple rules and you will succeed.

Finding good mailing lists is not easy—it will take time to partner with a list broker, to educate yourself and to set up your learning cycle. Be diligent, however, because it's well worth it. With 40% of the success of your direct marketing campaigns riding on your list selections, your efforts will certainly be rewarded. Follow these four simple rules and before long you will be getting the best results you ever had. And, of course, you will then set your goals even higher.

Joseph Pych is president of NextMark Inc., a Hanover, N.H.-based provider of list information and technology. He can be reached at jpych@nextmark.com.