I scrapbook my creations. I log the fabric line if I know it (I've gotten better about this through the years), the pattern, and I include fabric scraps or an extra block too. There is an app I've been using that's made documenting as I go so much easier-it's called the project life app. Right now it's for apple only, but it's sensational for this type of thing.
Wheni did did the wedding ring quilt last year, I was able to take pictures and write up every step of the process. If I ever make one again, I'll know exactly what I did.
Plus us ones ice gifted I usually stick the thank you note in there too. Fun to look back and reminisce.