The risk of infection is high. The skin will appear red, usually with charring. Pain is severe unless nerves have been damaged. In that case, pain is only at the periphery of the burn. This type of burn requires skin grafting, and will heal with dense scars.
Infection is a major concern.
Fire Wet or smother the burn. Remove smoldering clothing ONLY if it is not stuck to the skin. Tar,Grease,Wax Cool with water, do not try to remove substance from the burn. Electrical Remove person from current. Chemical Rinse the burn with a lot of water for at least 20 minutes.