I chose 8 categories based on what type of recipes I use most:
Appetizers, Snacks & Beverages
In the front of the binder, I included an extra sheet protector so that when I want to make a recipe from the binder, I can keep it safe while cooking! No more recipes splattered and ruined! Why did I never think of this before? It may not be a fancy system or a cute little box of hand-written cards, but this works for me!