Copy
The rest of the ad should simply get into detail about whatever benefits you chose in your headline as well as more information on other less important benefits that are still worth mentioning. How much copy should you get into? That depends on a few things.

Well, the first thing you need to consider is how much information does the target customer need to have in order to believe that they should go to that particular place instead of where they might be going already? If it's a product people are likely to be unfamiliar with, like a new water filter technology, then you might need to get into more detail about the product. If there's a brand name associated with it that everyone trusts, like Sony, you might not need as much copy to show how good it is as compared to a place that makes handmade furniture.

If you have the space, don't be afraid to use lots of copy, or long copy, as it's called. Some people won't read it all, but the people who are about to buy the product might consider it to be the most important item in the newspaper that day, and they'll devour each word. And remember, people who are buying and reading your newspaper are readers. They like to read. And they'll have no problem reading your ad.

The idea that you've got to keep it simple or people won't read it is just part of newspaper advertising design folklore. A great book to get on advertising is Ogilvy on Advertising. It was written more than a few years ago, but it will give you all sorts of advice on ad design and almost all the advice is backed up by actual ads that the author, David Ogilvy, was personally involved with. There's actually a full page New York Times ad in there for Merrill Lynch that had more copy in it than any page ever had previously in the New York Times, but the ad response was overwhelming. You can get the book any most bookstores, or at our website. I used to share pieces of information I found in this book with potential advertisers to show them that although I was new, I knew a lot about advertising and could help them. So don't hesitate about getting into detail in your ad--product descriptions, prices, processes used, guarantees, etc.