A tip I can give is that Cast Members are actually human beings, with full human qualities, which entitles them to make mistakes. If one does make a mistake in front of you, tell them it's okay, and smile. It will make it a lot easier for them, because as a Cast Member, we HATE going up to a guest and telling them what they don't want to hear.
Some examples that we envision in our head what will happen:
CM - "Sir I'm sorry I forgot your fries, I'll get them right now."
GUEST - "::long sigh::OH GREAT! THIS GUY FORGOT THE FRIES!! YOU BETTER GIVE ME MY MONEY BACK FOR IT!!!"
CM - "Sir I'm sorry I can't do that, I can go get a manager if you'd like."
GUEST - "No whatever just hurry up."
Or don't get mad at us when we are doing our jobs and looking out for your safety and best interests.
CM - "Welcome to Epcot everyone, for your safety, please walk in front of the parked cars for your safety, and also so you don't hold up traffic."
GUEST - "You know, you charge us $14 to park and make us park a %#%$^% mile away, don't tell us where to walk."
CM - "Okay"
::traffic holds up due to guests walking in front of incoming traffic::
GUEST - "You know if you parked us up front here we wouldn't have to walk in front of the parked cars."
CM - Just doing my job sir.
Some examples that we envision in our head what will happen:
CM - "Sir I'm sorry I forgot your fries, I'll get them right now."
GUEST - "::long sigh::OH GREAT! THIS GUY FORGOT THE FRIES!! YOU BETTER GIVE ME MY MONEY BACK FOR IT!!!"
CM - "Sir I'm sorry I can't do that, I can go get a manager if you'd like."
GUEST - "No whatever just hurry up."
Or don't get mad at us when we are doing our jobs and looking out for your safety and best interests.
CM - "Welcome to Epcot everyone, for your safety, please walk in front of the parked cars for your safety, and also so you don't hold up traffic."
GUEST - "You know, you charge us $14 to park and make us park a %#%$^% mile away, don't tell us where to walk."
CM - "Okay"
::traffic holds up due to guests walking in front of incoming traffic::
GUEST - "You know if you parked us up front here we wouldn't have to walk in front of the parked cars."
CM - Just doing my job sir.


)
Well worth it, though!
It's not like it's an insider secret that people aren't clued in to when they're announcing it
They are complimentary and the grown ups can wear them too! 
