I used a moleskine for my system for three years, until I finally bought an iphone and started using Google Tasks and two apps to sync everything.
My projects lists, which lived on the last pages of my moleskine, were just the title.
I have an old saved podcast here somewhere with Meg Edwards and I think DA, too, where they point out that the question of "How do I keep my projects and NAs linked?" is a question asked by people who aren't actively practicing GTD, who are at the outset of implementing GTD, or who aren't fully harnessing the power of the weekly review.
As GTD becomes as comfortable for you as answering a phone call, you'll start to install things such as jotting where your project support materials are, or you'll be rocketing through NAs on a project so quickly you don't need to remind yourself what the next step is--it will be apparent.
And you'll sweep up behind yourself once a week.