Clothes can very easily catches fire and within seconds it can spread to all over your body and the victim will be in flames without even realizing what to do.
To save the victim from becoming another victim of fire you should follow Stop, Down, Roll & Cool steps. This is the most basic way to stop the fire from spreading and killing the victim.
Stop any movement which may fan the flames and speed the spread of fire. Though this is very difficult in such a situation to halt movements but this is the first thing you should do.
The second thing which should be done is lying on the floor which will deprive the fire from oxygen from at least half of the body. Use hands to cover your face and avoid facial injury.
Now roll on the ground so that fire in all parts of your cloths will be deprived of oxygen. If possible use rug to roll it completely on the body of victim ending the supply of oxygen for fire.
If the burns are first or second degree then use cool water to lower the body temperature and prevent the burn from becoming worse.