I keep a yearly "diary" of quilts and projects, yardage used, fabric samples and pattern names. I include who the quilt was given too and sometime what I would change to make it easier. It has taken years and years to figure out just what info I want to keep. I write a list monthly of what I want to finish, seldom get that done, but it does help me focus on moving ahead. More importantly and more consistently done, are photos. I take a picture of every quilt, pop it in a folder on my computer with the date of completion as the first item in the title. New year is coming and a new folder and little spiral diary. Always a grand intentions to finish more.
I tried the published diary types from other sources but they did not fit "me" and the info I wanted to save. I use a smallish spiral bound notebook that has three sections, so I can use it for three years. Works for me.