Keep it short.
I send out a lot of emails, to you lovely creative lot, to my web design customers and for clients, and the results are really clear: shorter emails work better.
In fact, there’s a part two to that: short emails that ask a question work best.
The best response I’ve ever had for an email was two sentences, asking my customers what their marketing challenges were at the moment. The subject line just said “Quick question for you.”
This worked for two reasons. First, it sounded authentic. It was the kind of email you might get from a colleague. There was no mass-mail feel to it (which is also why I recommend against using fancy HTML email designs for your creative business). Secondly, it engaged with the reader. It valued their opinion. It encouraged conversation.
Now of course you can’t do this with every email you send out. You have to provide useful content too. But in a world of unlimited content and tiny amounts of reading time, the power of the short can be a great way to cut through the clutter.
REMINDER: Don't be TOO vague with your subject lines. If people feel they're being tricked into opening an email, they'll probably unsubscribe. Be vauge but on-topic. Rather than "Hey" try "Hey, can I ask you something?"