Holi is a festival in which people throw colours at each other. This symbolises the exuberence of life. So being joyous but at the same time being conscious, aware and alert is important.
Over excitement may sometimes lead to a mysery. So it is advisable that you do every act with full consciousness and alertness.
Some people may have allergy from colours while others may have sensitive skin or skin disease. So it is recommended that you should ask the people for permission to apply colour on them.
Also some children throw water baloons on the passing by vehicles which may deviate the drivers attention and may lead to an accident. So be cautious of this act.
Also the chemicals used in the colours have potential to cause rashes and etchying. So one should use herbal colours and also apply some oil or protective lotion.
People have tendency to eat sweets while playing holi. This can be very harmful as the toxic chemicals may enter the system. So dont do the two things simultaneously.
Beware of the electric wires and transformers.
Wishing you a very exuberent and happy Holi!