I keep a loose leaf notebook so I can easily take out and put in pages. I keep:
1. Picture of project if there is one
2. Graph paper "picture" of project with all measurements and if the projects have blocks I draw how a block is put together
3. Snip of the fabrics glued to another page especially mostly so I won't forget. I bag the fabric with the name of the project on it and shelve it. I think those are called "PIGS" or "Projects In Grocery bags".
4. On the back of the graph paper or even on the front I put start date, sometimes if applicable the "done basting" date, "done quilting" date, and "done binding" date and so on.
5. Photograph and where the quilt is now.
6. I ask to have problem items sent back to me, or at least to tell me about any problems and I record that information, too. Also if the quilt has been sent to me for washing! Yes, it happens!
I have some information on almost everything but looking back, some of the photos were pretty poor and I wish I'd been fussier about getting a "Good" picture every time. Since I know where the quilts are I've been thinking of asking people to take photos for me, the digital photos are much better, so are the photographers!
Oh, yes, I used to keep a list of projects I had supplies for and projects I wanted to buy fabrics for but it got way, way too long!
Jois