I use a graph paper notebook for my quilts. I sketch the entire project or at least a preliminary sketch. This helps me plan out all the pieces that I need to cut in terms of dimensions and number. Usually, I also draft a plan for how to sew the parts together. Also, lately I include stitch selection in terms of what did or did not work and any comments about useful modificatons. Based on the comments of others, I will start including photos of the finished projects.