Just like a direct sales letter, the subject line of your email can make or break your campaign. If you don't have a compelling subject line the chance of your email even getting read is slim.

According to a recent MarketingSherpa.com survey, 40% of email marketers said testing changes to just their subject line had a high impact on their return on investment (ROI). 45% said subject line changes accounted for a medium ROI and only 15% said that testing changes to their subject line results in a low ROI.

For every email you send you've got room for no more than 50 characters in your subject line, and today I'm going to share with you 10 tips that we use to increase the open rates of our email campaigns.

1. Test the subject line – Take a look at email campaigns you've sent in the past. Which subject lines worked the best and gave you the highest open and conversion rates? You might find that for a particular topic there's a general trend or subject style that resulted in higher open rates.
   
2. The subject of importance – Try and put as much important and relevant information into your subject lines as possible. For example, if you're sending out an email about a special offer make sure the product name and details on the offer appear in the subject line in a clear and concise format such as "$40 off ACME Widget Until - Today Only".
   
3. Personalize the subject line – If you have details about your subscribers then use them in your subject line to get their attention. A subject line containing the subscribers first name ALWAYS out pulls one that doesn't.
   
4. Avoid spam keywords – Most email servers automatically filter out any emails that contain spam keywords in their subject line – Words such as free, stock, ebay, password, mortgage, etc all trigger spam detection software so keep them out of your subject lines at all times.
   
5. Trigger curiosity – The best way to improve your open rates is to pique the interest of your subscribers. A compelling headline that entices them to open and read the contents of your email can do wonders for your conversion rate. I've been thinking about headlines that trigger curiosity, and if you can work this one into your email campaign I'd like to hear the response rate: "Hi [First Name] - I have a question for you.".
   
6. Make the offer clear – If you're making a special offer to your subscriber then be upfront and include it as part of your subject line. People love bargains and special offers so let them know about it before anything else.
   
7. Emphasize the benefits – We use this technique for our newsletters. We always use the format of "COMPANY NAME Newsletter – [Benefit]". In our case, benefit is always the title of an article contained in the newsletter, such as "Interspire Newsletter – 10 Tips for Better Subject Lines". It works every time ;)
   
8. Copy what works – Mitch recently wrote an article on the top 12 headlines of all time. Why not take some of these and use them in the subject line of your next email campaign?
   
9. Easy identification – Make sure your subscribers know the email is coming from you. Deceptive subject lines can confuse people so always try and including your company name in the subject line. Also, make sure you set the "From" attribute of your email to include your name and your companies name, such as "From: John Smith <john@acme.com>".
   
10. Exclaim nothing – Avoid using excessive punctuation at the end of your subject lines. Google bans punctuation from AdWords ad's for a reason – too much hype can annoy and confuse people.