Offering Subscribers Something Of Value

Though the sole goal of email marketing is to get subscribers to buy something you are selling if all you ever do is tell them about the products you are selling then odds are they'll unsubscribe really fast.

Offer subscribers something of value and they'll be eager to open your emails each time they receive them. You could send them reviews of other products they might be interested in [products which you probably don't sell], aggregate information which they'd otherwise spend lots of time trying to find all over the net, etc., etc.

Those two are but examples [not great ones I must admit] but fact is subscribers are more likely to read your emails if they are sure they'll learn something from them.