Get Customers to Open Your E-Mail Looking for a low-cost, high-return marketing tactic? Follow these four expert tips for a successful e-mail campaign.

Ask the majority of small-business owners, and they'll tell you the one tool they can't live without is e-mail. In fact, with its extremely low cost of implementation and quick turnaround time on campaigns, e-mail marketing is becoming the customer-retention tool of choice for entrepreneurs nationwide.

Just as with any other new marketing tactic, e-mail marketing may take a bit of time to master. If you've tried e-mail and had less-than-stellar results, there are a number of important steps you can take to improve your ROI. And if you're just learning about e-mail marketing, it's critical to understand the elements that can make or break your campaign. For superior results, be sure to follow these four important tips.

1. Build a Qualified List
Right now, e-mail marketing performs best when used for customer retention, not acquisition. With the proliferation of spam, most consumers are filtering out all but the most recognizable e-mail. In a consumer e-mail study by DoubleClick , the vast majority (93 percent) said they considered an e-mail to be spam when it came from an unknown sender, but the majority said they open at least 60 percent of permission-based e-mails.

To build your own permission-based list, prominently display a registration box on the main page of your website and provide an incentive to register. This incentive can be anything from notification of sales and specials or access to special content, to a free newsletter. If you have an e-commerce site, capture registrations during the checkout process and provide registered customers an incentive, such as speedy checkout on future purchases. Brick-and-mortar retailers can acquire e-mail addresses at the register.

Once you've assembled a sizable opt-in list of customers and prospects, you'll need an affordable (less than $50 per month) e-mail service to send out your campaigns. Choose one that also provides professional-quality templates for inputting your copy.

2. Improve Your Open Rate
Your customers and prospects can't act on your e-mail solicitations if they never open them. While open rates have been on the decline over the past year, conversions are actually rising, which is a strong tribute to e-mail as a successful marketing tactic.

Recipients quickly scan the "from" and "subject" lines and make almost instantaneous decisions about whether or not to open your e-mail. So always display a name your customers will recognize (either your own or the name of your company) in the "from" line. That will make it clear the e-mail is coming from you, a valued source of information.

By keeping your subject line short--no more than five words--it can be read in its entirety at a glance. The most effective subject lines include a customer benefit or at the very least a clear indication of what the e-mail contains.

While e-mail that comes too frequently--even from a recognized source--is often considered spam, sending e-mail too infrequently can cost you sales. In an e-mail marketing survey published last April by InternetRetailer.com , greater e-mail frequency was linked to higher response rates and more conversions. This study suggests that the most effective e-mail frequency may be two-to-three times per month, with half of the survey respondents in that group experiencing e-mail response rates of 5 percent or higher.

3. Make Your Content Relevant
Most internet users are on many permission-based lists, but they look forward to--and avidly open and read--e-mail with content that's specifically relevant to their needs. What would your customers and prospects most like to receive from you? Building a successful e-mail campaign hinges on sending messages that fit your list members' attributes and preferences.

Customers typically expect e-mail to confirm transactions and shipping, although many other types of communications are welcome. Nearly three-quarters of the DoubleClick survey respondents said they had redeemed online coupons, approximately half expressed interest in receiving information about membership rewards programs, and more than half of the respondents said they would be interested in offers for products related to those they purchased online.

4. Increase Click-through and Conversions
Click-through rates vary based on whether customers are being asked to click through to make a purchase or simply to get more information, such as by reading a longer article in a newsletter. You can increase click-through by offering multiple links sprinkled throughout your e-mail, so customers don't have to read all your copy in order to move to the next step. For e-mail solicitations, a strong call-to-action is essential and is largely responsible for a pass or fail click-through rate. Be sure to provide an incentive that adds value and gives your recipients a reason to respond now.

And here's a final tip regarding e-mail solicitations: For maximum conversions, direct your click-throughs to specialized landing pages on your site--not your main page. Send customers to pages where they can take immediate action on your offer, rather than having to hunt through all the pages of your site. This small adjustment will increase sales and the return on investment from your e-mail campaign.