just a few recent journal pages to show that you don't really need a boatload of 'art' supplies to do art journaling, depending on your artistic style and/or mood. Sometimes I really like making pages loaded with layers-- paint, stencils, stamps, collaged paper, tape, images, etc. etc. And then, sometimes I really like just the basics (well, my basics, anyway): paper, scissors, glue, and pen(s) or marker(s).
This page is mainly strips of patterned scrapbook paper, a floral design cut from SB paper, and a cute Japanese kitty I got from somewhere (I think it was Japanese note-paper or something), all glued down with a glue stick. (In all honesty, there is also a bit of lime green ink edging the kitty, but that wasn't really necessary.) I may write on this page later, I may not- but I probably won't add much of anything else to it design-wise.
To be perfectly truthful, while the page above is 'only' paper, glue, and pens, there's a lot of different kinds (of both pens and paper). The papers range from origami to handmade imported, scrapbook paper, vintage book text, and hand-made marbled paper (on the right edge of the page). The pens used on this page are mostly Sakura gelly roll glaze pens, along with my trusty Signo white gel pen. My art supply collections have evolved and grown over time (helped along by the fact that I also scrapbook- and the fact that I'm a bit of a packrat, lol!).
But, you don't need a huge collection of supplies to art journal; you can make journal pages with only plain paper and a ballpoint pen or a pencil if you want, or if that's all you have. (I have quite a few doodled pages in my journals that started out that very same way!)
Another page made with various papers, pens (only 2 to 3 pens were used here), and my trusty glue stick. I made the page frame with various papers, wrote the quote with a black pen, embellished a few of the paper designs with colored pens, and did a bit of doodling with the black pen. A couple more things I want to point out on this page: 1) I made a mistake on this page! I mis-wrote the word 'talk' in the quote, so I re-wrote it on a separate piece of paper and glued it right over the top. 2) my writing is not 'perfect' or 'artistic' here: I can't write straight, and no matter how much I might try, I don't have a 'flowy, artistic' style of handwriting.
Just a couple more lessons for me (and maybe you, if you're reading) to take to heart: it's your journal, and it doesn't have to be perfect. It has to reflect your moods and your (current) artistic style, and be full of supplies and techniques that you like.