Whenever I create a load, I record what I did on a 3X5. I shoot targets with most of my loads. When I do that, I shoot an 8 1/2 X 11 sheet of 3 ring binder paper. I put all the same data right on the target and then file it in a binder. Extreme spread, range, etc. is recorded on the 3X5.
I organize the cards and targets by caliber. If I am getting lots of data in one particular caliber, I then divide the cards and targets by bullet weight. I could further subdivide by powder type if I really had a lot of data. When I get rid of a gun and am not reloading that caliber again, the cards go in a different "dead file" box.
I guess you could take pictures of your targets and keep those on your computer, but I have the real thing. Sometimes, when I go back through old targets a see something that I hadn't taken note of before like stringing .