Make it easy to subscribe. Post a signup form on your homepage, blog, Facebook page, and wherever else your customers and fans are already active. You might want to collect names and birthdays (for a special offer or gift) or invite readers to join groups, but don't go crazy with the required fields. A too-long subscribe form might scare people off.
You can assess the interests of individual list members by monitoring which pages they land on, and where they go from there. The process is explained by this example from Airbnb. They use click behaviour to ascertain the destination preferences and travel styles of customers and base their follow-up emails on those preference profiles. It's intensely specific, but it gets results!
Whenever possible, add a personal element to your emails. Most email tools allow you to enter shortcodes that will be replaced with the recipient’s name when the email is sent out. Emails from Treehouse Co-Founder Ryan are always fun and personal. The subject lines are creative, messages are sent "from" Ryan's email address, and the content is personalized. If you reply to the mail, you'll even get a prompt response from Ryan himself!
Will people understand what you’re trying to say? It’s usually better to avoid topics (or opinions) that are complex if many people are extremely passionate about them. For example, sharing almost any opinion about immigration policy is usually a bad move, unless your audience is unusually homogenous. You could agree 99% with someone and still piss them off by using the wrong term just because they have such a strong “either you agree 100% with us, or you’re our enemy” mentality. I once pointed out that I think it’s unacceptable to capture and torture people for years—especially if they aren’t charged with any crime, there’s no evidence they’ve done anything wrong, and they’re children. I got several emails back from people saying, “you have no idea what you’re talking about” or “you should stick to marketing and leave politics to people who understand it.” They took it as commentary on geo-politics. I just said I’m not okay with pointless torture of children. I thought we’d all agree on that.
Remember when I said a lot of your email recipients will scan your email without reading all the copy? That's why you want to have a clear call-to-action (CTA) button that's easy to spot for even the quickest of email scanners. Without a CTA button, you won't be calling on your recipients to take any action that actually benefits them -- and the growth of your business.
It's important to take advantage of the window of opportunity when your company or brand is at the top of your prospects' minds. You can really get a pulse of what future engagement will look like by what people do when you email then within 24 hours of their subscribing to your newsletter, signing up for an offer, and so on. Plus, it's a great opportunity for branding and setting expectations.
When you're using email as a marketing tool, you're working on a pretty personal basis. This isn't ‘drive-by' stuff -you're directly targeting customers from their inboxes. There's a huge amount of potential which comes with this kind of marketing... but you'll only reap that potential if you REALLY understand both the marketplace you're operating from, and the audience you're talking to.