Before I got into OmniFocus, I used Evernote for GTD. I had a few different structures, but I think I ended with a simple setup that worked well for me before I outgrew it.
I am so glad this is back! Many years ago this series changed my life. I’ve written about it here: https://theuncannyvalley.net/2019/12/12/its-productivity-time/
Amazon.com : Rhodia A5 Webnotebook, Dot, Black (47391EX) : Wirebound Notebooks : Office Products