What is a good subject line?
The subject line is the first thing that people see, and often determines whether or not they open your email. Here are some tips on writing your subject line:
Keep it simple
Keep it short and simple. Try to write it so that there are fewer than 10 words; in fact under 5 is even better. Keeping your subject line down to a few words will make your email seem more credible.
What's in it for them?
People are always interested in one thing: What's in it for me? Write with that in mind - which means write about the benefits that matter to them, not features that matter to you.
!!!
Don't use exclamation points at the end of the subject line. Question marks are okay, if it suits the subject. Questions are often more engaging than statements.
No Sales Lingo
We are surrounded with flashy sales stuff and it is now an automatic turnoff. Avoid words like "limited time," "free," "opportunity," and "only." Doing so may hook some; but it will turn off many more.
Love at first sight
When people first look at your email it has to grab your recipients' attention and engage them to keep reading, so keep the interesting stuff at the top.
Want more information? Check out Bryan Eisenberg's article, where these tips are based from.