Your art journal can be anything you want it to be. I say "Make like Nike....and just do it!"
I made mine from an old daytimer and use it for my calendar, SB, stamping and drawing journal. I used Wasau 110 LB cardstock (you can get it at M's with a coupon). Copics bleed a lot on that cardstock, so I Copic on better paper and collage it on the pages. The format is a process...continually changing. I use Copic pens and color with Copic markers.
I have not done any drawing since I was in HS in 1966. Big mistake. I've recently found Zentangle and enjoy drawing one from time to time, too.
I don't finish a page, I work on it until my creative MOJO or time is out and will come back to it from time to time.
I still have clean up work to do from the Copic bleed through. I hope it inspires someone to just get started.