Some things to consider if you are : 

First on Scene to an Accident or Involved in an Accident

First on Scene to an Accident

Scene Management
C  -  Casualty
H  -  Hazards
A  -  Access
L  -  Location
E  -  Emergency Services
T  -  Type

Casualty History
A  -  Allergies
M  -  Medication
P  -  Past medical history
L  -  Last Meal
E  -  Events / environment


Involved in an Accident

Stop at the Scene

Contact the Police if there is Injuries/Damage to Property

Exchange Names,Addresses, Tel.No. of all persons involved

Exchange Make, Model, Reg.No etc of vehicles involved

Make a sketch of the scene, noting street names, direction of travel etc...

Take photo's of the scene (mobile phone..)

Contact your Insurance Company