Eh, I think what's going to benefit you the most is creative design. Mario, for example takes simple concepts like mountains, hills, trees, and adds a creative twist. Also, keep designs simple and geometric. Cartoons don't like complex.
http://spriters-resource.com/ds/news.../forestbgs.png
Look at the trees. Tree trunks are simple in shape, nothing but straight lines. Simple shading to compliment the simple shapes. Then you have the designs themselves, which feature of course, simple circles
You also have exaggerated Flora with bright, vibrant colors(well, sort of... since it's a background it gets background priority, aka darkened) and bushes are simple, and resemble fans.
http://spriters-resource.com/ds/news...ncanyonbgs.png
Mountains take on a very comical design. They're pretty much shaped like cones, and almost resemble an icecream cone because of the folding occurring.
http://spriters-resource.com/ds/news...asslandbgs.png
Here you have the traditional "hills" you'll often find in Mario. Simple shapes, again, very geometric. Colorful designs that you wouldn't normally find in natural landscapes. And lastly, you have the familiar shapes thrown all around on the hills. You also have very simple clouds instead of very fluffy and complex clouds.
All in all, keep it simple and get creative with it. I only used Mario here but look around, you'll see a lot in common with cartoony backgrounds that mostly come down to simple design not venturing far beyond elementary geometrics, bright colors and funny designs!