When it comes to expanding your client list, rented or purchased mailing lists are an efficient way to generate new leads and market your services to a new demographic. In order to be cost-effective, however, it's important that you avoid some common pitfalls when purchasing and using new mailing lists.

Whether you're using direct mail marketing or email marketing, the success of your campaign starts with the quality of the mailing list, but it doesn't end there. These common pitfalls will sabotage your marketing campaign and make it less effective. Avoid them and you're guaranteed a high response to your direct mail marketing materials.

1. Acquiring a Mailing List Before Developing a Marketing Plan – Mailing lists are marketing tools that work best if you have a pre-defined place for them in your campaign. Define your target market, then acquire a mailing list or you risk letting your mailing list define your marketing materials instead of the reverse.

2. Buying General Mailing Lists for Targeted Products and Services – Sending out direct mail marketing without a target is like throwing confetti in the air and hoping some of it lands in a pre-defined circle. Targeted mailing lists cost a little more than general lists, but you'll be putting your marketing materials in front of people most likely to buy from you. Because you'll get a higher rate of return, targeted mailing lists will actually cost you less per sale than using a more general list.

3. Sending Out Direct Mail Without a System for Measuring Response Rates –  Mailing lists, especially targeted mailing lists, are a direct investment in your business. You'd never make a monetary investment without some way of measuring its return, and a mailing list is no different. Make sure that you devise a way to measure the effectiveness of each marketing message you send out so that you refine your marketing materials and make them more effective.

4. Putting All Your Eggs in One Envelope – Many businesses devise one direct mailer and send it out to everyone on their mailing lists. Savvy marketers work out two, three or even more versions of the same marketing message and test them against each other to see which is the most effective. Divide up your mailing lists and send a different version of your mailer to each list segment so that you learn which colors, text, graphics and calls to action are most effective for your product.

5. Failing to Follow Up – Experts in marketing will tell you that it takes an average of seven contacts with a potential customer before they are fully sold. Your marketing plan should include several follow-up contact opportunities depending on the response such as a letter to those who don't respond at all, a different message to those who express interest, a thank you message to those who make a purchase and follow-up mails asking for feedback after purchase.