This journal page is from Guillermo del Toro's concept art for a movie. Lots of creatives think by drawing, and an art journal is the perfect place to do this. The biggest hurdle is often worrying what the page looks like. Make a bunch of messy pages, add some ugly drawings, and you will be much freer in your work. and after you've filled a bunch of sketchbooks, look back through them, scan some pages, and collage into another book.
Seriously fun, and this always helps me come up with new ideas.
"The creation of an art collage from the soul is an inner journey that allows your soul to speak to you. Your soul's voice can be heard through the images, feelings and insights that surface..." --Kathleen Carrillo
"Rapid-collage prevents any elevating movement toward a fixed goal. To 'be nowhere' is to let oneself be." --Josh Goldberg
"Collage is like a hall of mirrors. Every direction you look, you see something different and visually stimulating." --Nita Leland
"Collage is the twentieth century's greatest innovation." --Robert Motherwell