Here is an area where I'd like to add some fibers:
First select some fibers in colors that work well with both pages. Vary the thickness and texture of them, and make sure they are several inches longer than your book.
Put some double sided tape right down the center on the spine, covering any of those raggedy bits of paper.
Remove the protective paper from the tape.
Gather the fibers together and press them into the tape, making sure that they all stick, and that all the tape is covered with fiber (so your pages won't stick together.) Allow several inches to dangle off both the top and bottom of your pages. You can leave them as is, or add some additional interest by knotting some, or even tying some beads on.
Of course, you are not limited to the spine of the book when it comes to adding fibers. You can place your tape and fibers anywhere on a page. Nor do they absolutely have to dangle off the edges (though I do love how that looks). You can create a frame around a photograph with your tape and then add the fibers.