John Jantsch has an interesting post in the Duct Tape Marketing Blog about how many ads fail to ask the reader to do anything:
By grabbing your reader, viewer or listener’s attention and making them do something, you stand a much better chance of them following through to the ultimate step of buying or becoming a client.
The same goes for your newsletter. It’s important to give them a chance to take action after reading your newsletter. That’s how you’ll make your newsletter effective. The best way to do this is by creating an offer.