All right, I think I have it figured out: I saved elements in folders by designers so I know whom to give credit. I also saved them by theme, so that I have all fall theme elements together, all baby theme elements together and so on. And lastly I printed the preview pages for each kit and use this as a catalogue. Flipping through the catalog pages seems to be much quicker than looking through the folders on my computer.
Thanks so much for all your input. Yes, it took a while to get it all organized. But I like my system now and I can actually find stuff.
