I've recently started scrapping again after a year's absence (hi ladies!) and am so glad I adopted my system of organization early on. After such a long break, I'd never find anything if I hadn't!
First I downloaded a free program by Sierra called File Amigo (you can Google it). In it, I have two tables, one called Catalog, the other Layouts.
The Catalog file contains columns for DVD volume number (for backed up scraps), kit name, credits, keywords, up to 3 previews, and colors. There are check boxes for commercial use, quick pages (as my time has gotten more valuable, I've come to appreciate QPs much more, especially for scraps other people ask me to do, like my mother), templates, and one for if I've used the kit. I keep a copy of all the previews in a folder called previews, titled with the designer name_product name. The database file can be exported into a tab or comma delimited file for easy backup. When I'm looking for products for a specific theme or containing a certain color, I can just do a fast find (i.e. Christmas kits or kits containing the color blue). If I only want templates, I do a specific search where Template = Yes.
The Layout table contains the layout title, a preview of the layout, and the credits.
I'd be happy to give anyone who wants it a tab delimited file of my catalog if you want to use it to adopt for your own scraps.