This a very interesting topic, since organized is one thing I'm not!  I downloaded a list of categories, but should have deleted the ones I didn't need, because it got very confusing.  For a while, I used that part of Designer;s Gallery, but after a while, I couldn't figure out how to use the rest of it.  I finally included it in the sale of my Babylock.  If I could purchase just that one module, it might be worth a try, since it opens, converts and stores designs.  If it didn't take so much time, I would go through all my designs and delete the ones I don't need.  When I bought my first machine, the saleswoman gave me the addresses of websites where the designs are free, but at some point I was told that most of them were from beginning digitizers, trying to become better known and they didn't always stitch well.  I'm too impatient to test those kinds of designs.  I have my favorite digitizers, and their designs usually don't need to be tested.  For a while, I tested designs for someone, and found that her designs are always perfect.  I graduated to watching them stitch out, and was fascinated by how few stitches were created to get a beautiful design.  I'm not interested in digitizing, except to gain insight as to what processes produce great designs.  I'll leave the rest to those who are good at it.  As to the organizing, I have them  filed two ways - by designer and by category.  But as the others have already said, it's a very individual process, and the best you can do is try what systems you like, and modify them to suit your needs.  Good luck!  I'm sure you'll come up with the best system for you,