Draw a border around your paper and then create a random walk of dividing lines to create sections within the box. You can use straight lines or curvy lines, whatever you wish (image 2).
Proceed to fill each section on the page with a different repetitive pattern. The more artistic can really go to town here though people like me (with no ability to draw) can still get nice, attractive results (image 3). Do a google image search on zentangle for many, many examples.