When it comes to deciding how to craft that perfect subject line, there appears to be really only one area to avoid: the subject line of 60 to 70 characters. Marketers refer to this as the “dead zone” of subject length. According to research by Adestra, which tracked over 900 million emails for its report, there is no increase in either open rate or clickthroughs at this 60-to-70 character length of subject line.
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.