The first major hurdle to overcome is getting your lead to read the email in the first place.
Writing an evocative subject line is crucial. When your email arrives in someone's inbox, the first thing he sees is the subject line – and if the subject screams “salesperson” he won't even bother to open it. He doesn't know you, so your email address won't mean anything to him; the only thing he has to judge you on at this point is the email subject.
Don't give in to the temptation to write a deceptive subject line like “Re: yesterday's meeting.” You'll get your email opened all right, but as soon as he realizes he doesn't know you, you've just lost any chance to sell to him. The same goes for the body of the email. For example, some salespeople imply in their email subject or body that they've already emailed or called the prospect. If you really did email him, forward your original email so that he can see what you're referring to. If you really called, include a synopsis of your conversation or voicemail message.
Once you've come up with a good subject line, the next step is to craft an opening phrase that will keep him reading.
This phrase should be similar to the hook you use in cold calling. In fact, if you have a good cold calling script, you can modify it and use it for emails as well. Just don't use it in an email to someone you've already called using the same script!
The very best opening line would be one that you customize to fit the prospect. For example, let's say you read a news article about a new tough regulation that affects a particular industry. Your emails to leads in that industry might start with, “Have you worked out a compliance game plan for Regulation X?” Then you can continue with a description of how your product or service can help with that need.
Don't use graphics or fancy formatting in your email. Ideally, it should look like an email that you'd send to a colleague at your company. Yes, it's not as pretty, but it looks professional rather than like a piece of marketing collateral, which means prospects will be more willing to read it. Also remember that some email clients won't download images by default, so if you include a lot of pictures then those prospects will get an email full of holes.
If you have something of value for the prospect, such as a white paper or how-to article, include a link in your email. People have a natural instinct to reciprocate when someone does something nice for them. If you give a prospect something useful or valuable without being prompted, he'll be strongly inclined to at least schedule an appointment with you.
Email prospecting works best in combination with other prospecting methods. Phone calls are a particularly good complement to email because phone calls are real-time and immediate while email is more impersonal. Many people prefer one or the other for communicating, so if you use both, you're more likely to connect with your prospects.