Has your friend been scrapping for a while? If so, she probably has an idea about how she searches for items. I think knowing how you look for things is the first big step to the process because how I look doesn't work for some of my friends. I have some friends that only tag the previews and one that only tags papers but she tags them in minute detail.
I would be more than willing to share my categories in ACDSee but mine are pretty detailed.