I've often said that I don't just randomly glue stuff down solely for the sake of covering a page. I've been doing this long enough to have amassed a decent size collection of ephemera and stuff that's relevant to the way that I work. In other words, I know what colors, images, symbols, patterns, etc... that I am drawn to.
Usually I tell my students to start by collecting a small pile of background papers and a few focal images that appeal to them and to place in their pile whatever catches their eye. From that selection, you can start to create a page.
When I go to create a page, I don't worry that every piece of paper has a meaning. I've already established the importance of the paper (to me) by placing it in my stash and sorting it aside for using NOW. It's something that happens without me even being conscious of it.
As I start to select my papers to use to create a page, I tend not to worry about anything other than choosing what I like to reflect my current mood and what I might want the page to say. In other words, I start by picking what I like from my now stash.
I picked the papers on the page above: the one that says Boston (where I'm from), the astrological chart (my friend, Krista made it for me and it's my birth chart) and the image of the girl who looks upset, wandering and wondering (perfect for my mood the moment I created the page.) The other papers and ephemera I chose because I liked them and they fit the mood of the page. I tend to sort through my stash quickly pulling aside anything that catches my eye, makes me stop and think, "A-ha!" and is relevant to the page that I'm creating. I start by picking what I like. I use certain colors and repeated patterns and symbols because they mean something to me (yes, folks, I use a lot of pink for a reason...) I only know this because I've been repeatedly working and creating in journal form for quite some time now. I can look back on my pages and see these repeated images, symbols, colors, etc... It's like I've developed my own visual vocabulary that's specific to ME.
All that said, don't stress and strain that every thing you do has to have meaning. Start by picking what you like and go from there. You can create your own meaning as you work on your pages. Play. Experiment. Explore. See what evolves and develops on your own pages. You'll soon realize that you have created your own visual vocabulary!