Way too much stuff! We are high maintenance travelers.
I have one backpack that hangs on the handles of my scooter that contains my camera (I mainly wear my camera though), extra lens, flash, my many prescription meds, Tylenol, Meclezine, band aids, sunglasses, hand sanitizer, sunscreen, colored sharpies, bags of nuts or other protein packs, clips for hanging stuff on the basket (such as our cups), trading pins in a ziplock, extra hair bands/clips, wet wipes, and travel size tissues.
In a second backpack, that hangs on the seat back, we carry blankets, my daughter's hoodie, water bottles and cans of soda.
The autograph book goes in the basket and my jacket/hoodie drapes over the back of the seat.
Around my neck I hang my phone on one lanyard and I have a small Disney coin purse that hangs on its own lanyard. In that I keep my ticket, fast passes, lip balm, cash, ID, room card, photopass cards, etc.