People who are good at composition have to exercise a lot of self-control.
Instead of starting a picture with small details, they instead have to plan a big visual statement that reads clearly and simply. I've picked a couple simple Eisenberg images to demonstrate this.
The overall image above is broken into 4 basic shapes. Then each major shape is again broken into subdivisions.
Then the next level.
Someone with less control would get all absorbed in the details early on. Maybe he'd start by drawing a bunch of individual leaves and hope they ad up to an overall tree shape. Or he might do a wild pose of the character - with all the limbs sticking out in every direction, and no overall silhouette.
Good layout artists have to have this kind of self-control - to avoid getting lured into the details too early. I wish I had Eisenberg's control. I've always struggled with composition, because I want to get right to the character.
Here's another example. The characters look great, but they fit perfectly into a much simpler framework, which helps them read well.
Ranger, Cindy and Baba Looey act as one form, that in turn fits into the bush shape behind them. They together are well separated from Yogi, who is the focus of the picture. Boo Boo looks up at Yogi and is framed by the bushes behind him. If all the characters were evenly spaced and the same size, the picture would be confusing and wouldn't draw your attention to anything in particular.
The characters and BG also frame the skywriting plane in the BG.
You can see this deft arrangement of shapes in all of Eisenberg's pictures.
Great illustrators like N.C. Wyeth use these exact same principles, only apply them on more complex levels with more complex drawing:
You can still see the big shapes dominating the compositions, and the details being subservient to them through many levels.
...and great use of negative space