Since the infancy of direct-response marketing, a targeted and captive audience has been the key to success. It didn't take long for "the list" to become king.

Though your list may remain the most powerful pillar of your direct-response effort, you also need strong, motivating offers and spot-on creative to go with it. Still, without the ability to reach the right people, the most enticing offers and the most exceptional creative take you nowhere.

In online marketing, when it comes to lists, the email-marketing list reigns supreme. But for most email marketers, continual email-list growth is the Achilles' heel of email marketing.

Neither side of the list-growth dilemma is pretty:

• Prospect lists. You have to constantly replenish the pipeline. For every sign-up you get, there's a potential unsubscribe. Most email lists are in constant motion, with people coming and going all the time.
  
  You can't assume that every subscriber is going to stick around indefinitely or that every prospect will become a customer. Yet without enough new list members, you won't have enough prospects who'll become customers. So how do you keep the influx flowing and greater than the outflow?
• Customer lists. Achieving 100% email-address coverage on customer lists seems impossible. Unless you're a pure-play online business for which an email address is required for every sale, some customers are just never going to hand over their closely guarded email address (or the specific address you want).
  
  Others now prefer to communicate via social-media sites (largely Facebook and Twitter). Still more are happy to remain old school; they want phone and direct-mail communication. Send them catalogs and coupons, and they're content.

So, how do you entice newcomers to join your list and then convince those eventual customers who haven't yet handed over their email address to finally give it up?

In Part 1 of this series, I'll share prospect-list growth tactics and then move on to customer-list growth strategies in Part 2. I'll wrap it up with list-engagement essentials in Part 3.

For now, here are three immediate steps you can take to attract new prospects to your list.

1. Content Marketing

Want newcomers to join your list? Entice them with worthwhile content that they can get only by subscribing?for free, of course. Share insight, knowledge, news, or exclusive information in exchange for their email address—the more exclusive, the better.

Content marketing is the lead-generation strategy behind countless webinars, teleclasses, free seminars, and white-paper offers (mine included). It's also the business model behind ad-revenue-driven websites and blogs on which content is accessible for free only if you're a registered user.

The challenge? You'll need to produce content or already be in a content-driven business to fully leverage the approach.

For those of us who aren't publishers or media companies, that means intentionally creating content in the form of a blog, video, webinars, audio, teleclasses, information products, e-books, or articles—and disseminating it (or links to it) as far and wide online as we can.

Yep, it's work, but it's an investment in your business, and there's no getting around it in the content-hungry Web 3.0 world. The more content you have distributed online, the more ways people can connect back to your hub—your business's website or storefront.

The great news is that once you have a content repository, you have a treasure trove of gems you can scatter around in Step 2.

2. Social-Media Presence and Promotion

Still don't have a Twitter account or Facebook page? Never checked out Bebo, MySpace, LinkedIn, or Digg, or even joined a Yahoo group (now, that's pretty old school)? Either you're living in a cave (unlikely, since you're reading this) or you mistakenly believe you can get by without those additional online points of presence.

Here's the reality: Social media isn't a flash in the pan; it's the new connective tissue of the Internet. Exactly which sites and communities will survive—and thrive—long term is still uncertain, but with upwards of 325 million users,  Facebook isn't going anywhere soon, you can be sure.

The beauty of participating in social-media sites is that they provide additional avenues for reaching your target audience and, naturally, inviting them to join your email list.

Social-media sites reach demographics and groups you otherwise won't cross paths with online. So get your social-media site pages and accounts set up, and start inviting and enticing friends, followers, and connections to the wonderful content you've developed (or are launching) in Step 1.

3. Joint Ventures and Affiliates

There's strength in numbers. A key to reaching more of your target audience is to find out where they're already hanging out—which, on social media, you will naturally see and do, in Step 2.

However, they might be hanging out on other people's email lists, which can be a good thing if your products or services are complementary.

Struggling with content development? Partner with a complementary company or specialist to create a new program, product, publication, event, or contest, or to offer new training.

If you can identify a complementary partner who already has a large email list that targets your ideal audience, you can offer to do much of the program development in exchange for exposure to the list. Or, your arrangement can be reciprocal.

Affiliate relationships are also great for list growth, although new rules as of last year require that affiliate relationships be disclosed up front, whether in email-list broadcasts or product reviews on blogs.

Normally, affiliates receive a commission on sales resulting from leads they've directed to your sign-up or buy pages, so you'll need an affiliate-program management system to record referring links and manage commissions, etc. Affiliate relationships can be reciprocal, or not.

As you're growing your email list, Twitter followers, and Facebook fans, keep one major point in mind (it's not a popular truth, but don't kill the messenger): Totals alone are meaningless.

Once you've achieved the growth benchmarks you want, the challenge isn't quantity, it's quality. How many of those 89,000 list members are actually opening, reading, and engaging with your emails? How many are buying? And how do you keep the momentum going?

We'll tackle those questions in Part 3 of this series, so stay tuned! And next time (Part 2), we'll address customer list-growth strategies.

A good email campaign is a great way to stay connected with prospective customers. Check out In Email, Emphasize Quality, not Quantity for tips on how you can keep leads interested and engaged.