Basically, you can create an art journal out of any mini-book you make.
Make sure you use the correct weight of paper to support your artistic endeavors.
Types of books to use:
children's board books (good place to start)
old books (in good shape and pages that can handle paint)
composition books
sketch books (with heavy weight paper)
Pages can be:
painted (gesso over print) with acrylic paints, water colors
Use of sketch pencils or colored pencils, pastels (set to prevent smudging)
collaged
painted, collaged and then use rubber stamps
Page designs:
can come from ads
scrapbook or card making sketches
Tips:
If using paints -- cover your area you are working in with newspapers or an old vinyl tablecloth. Do not wear your best clothing!
If using any spray items like paint or adhesive, do this outside on a non windy day.
Make sure pages are dried (paint or glue) before working on the next pages before or after.
Wax paper is your best friend for between pages while working on them or letting them dry because you need to add a weight to the top of a closed book.
Tin foil makes a portable mixing palette for paints.
Use a proper paper glue to glue in items.
Clear envelopes provide easy access to some paper items.
Recycled envelopes can house other paper items.
There are many examples of art journals online and over at Flickr, use a search.
An idea before you get started -- use a children's board book to experiment with painting techniques.
Pick a board book generally gesso and paint over pages, create sample sizes of paper to experiment with techniques.
These can be glued in the book and used as a reference if you want to create more art journals.
Or check out the video below to see how you can recycle cereal boxes to create a journal. If you use binder rings, you can keep on adding or subtracting pages.
Free e-course book by Kristal Norton (must provide email to receive)
Journal Journey blog has many art page tutorials.
Learn how to make a recycled art journal below.