Last month, we examined the important role the subject line plays in getting your contacts to open the e-mails you send. Now that we've established some of the dos for writing great subject lines, let's dig deeper and look at how you can make them powerful and compelling.

1. Ask a question. One of the best ways to get a reader's attention is to ask a question. But like a trial lawyer questioning a witness on the stand, make sure it'll get you the response you're looking for. "What's the best way to grow your business?" is a great subject line for business owners. After all, what business owner wouldn't want to grow his or her business? Or let's say you run a health club. An e-mail with the subject line, "How can you lose 5 pounds in one month?" would certainly be compelling. It's important your question be relevant to your audience.

2. Be a tease. A clever subject line can be enticing. When it's done right, reader curiosity is piqued. They want to know more--and they'll open your e-mail. Writing a teaser-style subject line requires some creativity, and your content needs to deliver. A company that sells high-definition TVs could use the subject line, "You're not going to believe your eyes" as a teaser to introduce a new addition to their product line.

3. Tell it like it is. Often, what works best is to say exactly what you want your reader to know. Examples of this straightforward approach are, "Sale on all sweaters this weekend," "Master jazz pianist plays live this Friday" and "The seven secrets of a profitable business." This just-the-facts approach works especially well when you can appeal directly to your audience's interests. It's also the best approach to use when you send a newsletter.

4. Remember "WIIFM." When a person gets your e-mail, the first thing they consider is "what's in it for me?" They have a decision to make. Do they open your e-mail, leave it for later or delete it? If there isn't something about the subject line that lets them know why it's worth their precious time to see what's inside, then the choice'll be clear. Keep WIIFM in mind when creating every aspect of your e-mails, including the offer, content, images--and most definitely the subject line. It's all about them. They know that; just make sure you know it, too.

5. Get personal. The more you can make each contact feel you're speaking directly to them, the more effective your communication will be. Whatever style of subject line you use, you can make it personal by using the word "you." Professional copywriters know the secret of using this powerful little word. Just look at the advertisements, mail and e-mail you receive. A few examples are, "Find the right swimsuit for you," "You can save 50 percent on travel," and "You'd look phenomenal in a custom-tailored suit." "You" is ideal, but "your" works too.

Not sure which approach is right for you? Try them all, then show a friend or colleague to get their feedback. Pick the one you believe will be most effective for your audience. Whichever approach you choose, it's always worth spending the time and effort to write a great subject line. Because if your readers don't open your e-mail, they'll never have the chance to read the important message you've created for them inside.