SAFETY IS AS SAFETY DOES! Translation flying a radio controlled helicopter is safe only if you are safe.
The rotating main blades of the helicopter, and the blade tip spins at 200-1500 rpm, with a blade radius of about 1 meter. It will easily cut thru skin and bones.
Never fly a model helicopter until you are able to control the helicopter.always fly in open space, and in the event that you loose control, no one, including yourself, will be in the way of a runaway helicopter.
Register your radio with your local telecommunication authorities, and get some form of insurance coverage if your model were to hit other people's property or life.
All these small precautions will put your mind at ease and you can then fully enjoy the trill of learning, building, and flying the most sophisticated radio control model every designed - The RC Model Helicopter!
HAVE FUN !!!!