As noted repeatedly throughout this series, when someone interested in your product or service voluntarily subscribes to your email list, they are doing a favor for you, not the other way around. This means that your invitation should be as friendly as possible to your visitors and should avoid things that most people find obnoxious or that feel like sales pressure.
One of these things to avoid is the use of pop-ups and pop-under requests to join your list. Many online marketers love these devices and swear by them, but realistically most people that encounter these devices online find them obnoxious. Realistically, if people want to go to a page, they click on it; using pop-ups and pop-unders essentially forces them to view something that they did not ask to see. Think of your own experience online, do you like it when you are hit by pop-up or pop-under advertisements? Probably not, and the same is true for people visiting your website. Another common, and related, technique is to make access to certain pages dependent on the visitor giving you their email address. This is just as bad and flooding their screen with pop-up / under advertisements and is just as likely to discourage people from exploring your content.
Further, today most web browsers have integrated pop-up / under blockers that actively suppress these messages anyway. There are variations on the theme that can beat these blockers, but again you are annoying the people you should be trying to impress. This practice is fundamentally counterproductive.
Similarly, many people ask for far too much information from their subscribers. To get the basic subscription, you should really just ask the visitor to enter their email address and then reply to the automated confirmation email that is sent to that address. You do not need to know their exact demographic information, their specific interests, or other personal information at this point. While such information may be helpful for your marketing campaign, you can solicit this in other ways and after they have already subscribed. One popular method is to offer the option of a customer survey – frequently coupled with a "free gift" incentive – which the subscribers can fill out after they are already receiving your email content.
While you want to make subscribing to your list as easy as possible, you also want to avoid too much pressure to do so. You can find some marketing websites out there in which every other line is actively encouraging its visitors to subscribe to their list. This makes your online marketing effort look desperate and also implies that you are far more interested in building your list than actually selling your product or service. Avoid underestimating the intelligence of your visitors, if you sound desperate for subscribers people will notice and be much less inclined to subscribe. After all, if you are that desperate, who knows what you are going to do with the email addresses you get or what kind of spam is going to follow.
Basically, when designing your online marketing operation, apply the famous Golden Rule concept, "Do to others as you would have them do unto you." Think of your own experience online, chances are things that you find annoying when surfing the Internet many others will find annoying as well. Visit your own website and try to objectively ask yourself if this is something you would subscribe to. Remember your website – as well as your email content – represent you to your potential customer base, so represent yourself well.