I have 4 categorizes for my dances in my card box.:
1. Easy contras
2. Medium difficulty contras
3. Hardest contras.
4. Triplets, circles, scatter mixers, etc.
Each dance clearly states the type: proper, improper, becket, etc. at the top of the card.
The thing that I can't do, but sometimes might like to do is to search for dances with particular calls such as hey, petronella turn, etc. That might be easier if I kept my dances on a tablet.
As I plan for a dance, I will go through each stack and pick out the dances of that type that I might like to call. And depending on the crowd, I can easily adjust the difficulty level up or down during the dance.