When communicating with children you need to be clear so they understand what is expected of them.
Make eye contact
Keep point short and clear
Think about vocab your using
Dont interupt children and never dismiss anything they are saying, this will only lower thier self esteem. Dont laugh or hurry them when they are speaking.
When communicating with adults you need to be respectful and consider thier point of view. respect all thier parental wishes. afterall it is thier child.
think about the method of which they prefer to communicate, telephone, email or in person.
There is just a few points off the top of my head.
Hope it helps x