The number one thing to do is to make sure your email template is mobile responsive. If you are using a mail service like Mail Chimp, that work is done for you. But if you are using a CRM that requires you to create the template, you want to ensure it is designed for mobile. Gmail can be especially tricky with responsive. Here is a great tutorial that goes over designing for Gmail: http://webdesign.tutsplus.com/tutorials/creating-a-future-proof-responsive-email-without-media-queries--cms-23919. But if you don't have someone on staff that does your web/email design and you're technologically challenged...this is definitely something to invest some money in a good template for.

Second, for email copy, you want to keep it short and your calls to action, near the top of the email. Think about how you personally read email on your phone...having to scroll down through an email, after a few scrolls, you stop and move on. Make sure you get your point across early so that people don't move on past your key message. All graphic emails and short infographics also do well on mobile. I love this website for inspiration for short or graphic emails: http://reallygoodemails.com/

Third, take advantage of the preview text in your email. Preview text is the snippet of copy pulled in from the body of your email and typically displayed underneath the from name and subject line in a subscriber’s inbox. You want to grab people's attention here so that they open your email. Here is a great article on taking advantage of this text. https://litmus.com/blog/the-ultimate-guide-to-preview-text-support