Fair question! When I pack with it I have three main items in the main compartment of the backpack. The first is my sleeping bag, and I'll be inside that. The second is my bag of clothes, this becomes my pillow. The last thing is a waterproof bag that mostly has my food in it, I put this right next to the tent or up in a tree depending on bears and the like.
Little things like my toiletries ziplock and phone are stowed in the area above my head. Any excessive stuff and my cook kit all live in the waterproof food bag, so it stays safely dry without needing to be getting in the way.
FYI, one of the rewards, the 20L Cuben Fiber Dry Bag, is what I use and we made it custom to fit in the Freestyle BivyPack like a glove. It works perfect!