I remember learning this on my first day as a journalist (February 2, 1998). Love how Nick Booth underlines how relevant the little things still are when it comes to being a good PR person.
Read more at www.microscope.co.uk
Pretend to be a journalist, and phone the agency up and ask if they can send you a picture. A good PR will know that a picture for a print publication needs to be in high resolution, at least 300 dots per inch, in Jpeg format and preferably a portrait shot.