Supplies
Stock up on Sharpie pens, magic markers, pencils, crayons, watercolor paints, etc. to add color and decorative elements to your page.
Collect a variety of images. I have several envelopes full of images that I have snipped out of magazines, clipped from newspapers, found on the ground or collected from other random places.
If a graphic or sentence catches your eye, grab it. You never know when you will be able to use it on one of your pages. If you really get into this journaling habit I recommend an accordion folder to organize your pictures by colors or words.
You can find all sorts of printed patterns and pictures in places you never noticed before. The inside of envelopes you get from the bank tend to have pretty patterns. Fortunes (from a Chinese restaurant) make a great starting quote for a journal page.
WARNING: If you print out an image on an ink jet printer, it will run if it gets wet from paint or glue.
Glue
The glue you use depends on what you plan to do on your journal page. For most pages a good quality glue stick will do the job. If you are using a thick almost cardboard like paper (think cereal box) you may need to use a liquid craft glue (Elmer’s school glue) and let it sit for 30 minutes. If you plan to layer over an image with paint or another medium then you will want to use something called “matte medium” if that is the case - Congrats! you are taking your art journal practice to the next level. Matte medium is a mostly transparent paste you can brush on the back and front of the image you are glueing. If you use matte medium the image will be bonded to the paper in a way that makes it pliable and easy to paint over.
An art journal is your personal place for expression and collection. You can use it to work through ideas, collect quotes or make quick sketches of your surroundings. I like to carry around a small bag with all my art journal supplies to pass time on airplanes or when I am in a waiting room (It’s a better than mindlessly scrolling on your phone.) It is very satisfying to look though all the pages you have done previously. It is like you have made a special book just for yourself - a small time capsule of sorts.