I've found that the best way for me to use Gelli Art mono printing is as background pages for art journals.
Generally I add them to my current art journal the same day I've made them; or at the beginning of my next art session.
I use a Rotatrim paper cutter to cut to a size a bit smaller than my journal page; fold it in half (or where I want the seam to be). Then I use an ATG double-stick tape gun to tape the edges of what will go on the right side of the jounal page.
Shove the taped/folded edge into the seam of the journal & gently roll it down. Then use the ATG gun to tape the back of the left half of the gel print and gently close the journal page.
This seems to allow for a smooth adhesion of the taped page. I patch together extra strips to fill more journal pages...no point wasting any of the printed page! Add wasi tape as desired.