A good, iconic image will always amplify the message of an article.
Further, I believe strongly that clip art is for sinners.
The curious thing about magazine illustration is that the content drives the image. Generally, otherwise incongruous elements will join to create a message.
The first illustration above was done for an article on the pitfalls of coastal construction. The second was for a story on building science.
Other times, the image is more straight forward, but surreal nonetheless. Like this one for a story on adding upgrades to your home before selling:
This one took on a more classic angle to illustrate opposition to the mortgage bailout:



