The "Dollar Bill Rule" is an easy way to tell if you have too few graphic elements on a page, too many, or just the right number.
Use just enough graphic elements to engage readers, but not so many you overwhelm them. Here's where "Dollar Bill Rule" comes in. Take a dollar bill. Lay it on your page. It should touch at least one graphic element (it can be typographical): an illustration, chart, pull quote, headline, photograph, or clip art.