Paint over your journaling. Use a pen that pushes into the paper or leaves raised 3D writing and the paint will catch on it.
Paint over your words first, then paint one big statement or title over the whole page with a paintbrush
Journal on a separate sheet of paper and then cut up to use on your page. (Here I turned my journaling into speech bubbles.)
Journal first in black. Then journal over it (same words) in white gel pen. Makes it hard to read but really looks interesting.
Glue an envelope to your page for very private journaling. You can put a letter in it, or a bunch of words on strips of paper. You can put anything you want in it. And you can seal it shut, too
Journal on a visually very busy background. (Here I journaled on a background that is collaged and painted.)
Use a pen that blends into the background of the page.
Journal one direction, then turn the page 90 degrees and journal over the previous journaling
Journal one direction in a color that fades into the background. Then journal over it, in an alternate direction, in a color that pops out. Make your journaling more general with the top layer. (Here I wrote: "This is a page about..." over and over.