I started out with a 3" heavy duty binder, but it wasn't a zipper binder. I was constantly dropping coupons from the top. Now I have a 3" Case-It zipper binder with a shoulder strap. I must say it is much easier now to transport. In the front zipper compartment, I keep a calculator, pen, scissors, and some of my business cards. In the file compartment, I have weekly ads, coupon booklets I have found in the store, and Internet coupons I haven't had time to cut. I also keep my pencil case containing my store loyalty cards and coupons I have pulled to use in the store that I'm in at the time. The zipper compartment inside the binder holds coupons I have found while in the store, loyalty cards to different businesses, rebate forms I have found while shoppers, etc.
My categories were very general in the beginning. (Examples: Baby supplies, Toiletries, Medicines, Cleaners) After I while I was sick of having to search through the entire toiletries category for the razor coupon I knew I had, so I broke the categories into more specific sections. Here is a list:
Store coupons specific to each store I shop
Hair styling products
Fabric softner/Dryer sheets
Furniture cleaning products
Air Wick products
Breakfast foods (cold)
Yes, I do know I have a lot of categories, but it makes filing and finding the coupons so much easier!! To label the categories, I bought the repositionable Post-it tabs.