You will speak differently to a four year old than say a two year old. With a two year old, the structure of your sentences may be shorter and simpler - because of their understanding.
Non Verbal communication:
You will use body language and gestures without realising as you ask a child to fetch something from the other side of the room, you will speak and point, when they bring it over to you, you will thank them and smile, children can read body language and understand the intonation of voice before they can understand words. Even as adults we take great store by gestures and body language; you know exactly what someone means when they say " She was flinging her arms all over the place and she had a face like thunder".
For all children you may have pictures around the setting i.e. over their coat pegs, or in the toilets picture signs with writing saying 'Wash your Hands' or 'Dry your hands'
For children needing support to communicate you may use pictures to help them understand what is about to happen i.e. you are all going to tidy up and get ready to go home.
You may you Britsh Sign Language or makaton sign language. You may have to use very simple and telegraphic language to a child with limited understanding.
You may use other props such as a balloon for a child to feel the vibration of words, but this will probably be with input from other professionals - they may have impaired hearing or vision.
You may use intonation for the child to know when you are praising them or when they or another child is in imminent danger.
You may have to get down to their level and make sure they can see your face for body language or lip reading.
When communicating with children, don't hurry them, let them take their time and listen until they have finished telling you what they want to,
What resources promote lanuage including ICT?
Well everything if an adult is with them, helping/scaffolding or...