For example check out this image from an amazing tangle group called www.tanglepatterns.com.
This amazing work is actually from Linda Farmer. As you can see she uses a number of different patterns.. which you can learn by visiting the referenced site, where you will find hundreds and hundreds of patterns to try out. Trust me it's so much easier than it looks.
So you ask what does this have to do with card making and paper craft? Well aside from the fact that it's art, tangle patterns can easily fill in your stamps making this art form even easier.
This is from onekraftykat.blogspot.com
This is from attemptedcreativity.BlogSpot.com
So some basic instruction is to get a stamped image that has a lot of hollow space and then start filling it in with the patterns you like best. There is no true right or wrong way to fill in your pattern - remember it's supposed to be fun, relaxing, and easy so practice and enjoy your doodling.