I tell any team that wants to win this award to have a genuine cause that they are devoted to. Teams should work as a whole and share a common passion while promoting their ideals throughout their community and FIRST. The days of throwing a food drive and a fundraiser are gone and this isn't the purpose of this award. Teams should be motivated and get emotional about it!
I really believe teams have to go big here, often moving the focus from the robot to their mission. Build season is only a short period of the year and the most inspiring RCA winners devote their entire year to other causes.
Essays from 2015 winners are a huge resource and share common threads.
http://www.firstinspires.org/node/4881