At my son's preschool, they take turns having a "special day". On that day they get to do the weather, be the line leader, etc. I decided to adopt this concept at home to solve all those pesky fights like:
"I want the green cup."
"I want to wash my hands first."
and surprisingly: "I want to let the dog out."
I wrote their names on magnets and keep their names on my fridge so I remember whose day it is.
That kid gets first dibs and it has ended so many minor battles in the past week.
Thank you awesome Preschool!!