1. Make it short:
Long email subject lines will be truncated and short email subject lines will be entirely visible in the email clients. When your subscriber opens their inbox the entire subject line will be seen and message will be conveyed entirely if you use short subject lines.
Sometimes you can not avoid long email subject lines. Then the best option is to keep a pretext at the beginning of the email.
Example of a short email subject line -
John, Increase Your online Income by $100.00 a day!
Example of a long email subject line -
John, Internet Marketing research finds the correct and profitable keywords in Four simple ways.
Example of a long email subject line with pretext -
Profitable keywords - Internet Marketing research finds the correct and profitable keywords in Four simple ways.
2. Personalize:
Call your subscriber by his/her name. Though this is very old strategy, it never gets old. People eyes get caught at their names. Few seconds of that time can be used to make the subscriber to go through the email subject line.
3. Keep it real:
Your subscribers are smart. They know the hype ... so don't fluff-up your emails with unreasonable claims and promises. Deliver what you have promised. Make sure your email subject line is out of hype. Let your email subject line increases the interest of the subscribers so they can click to open your email.