Keep the affected part elevated in order to reduce swelling
Move to a warm area to prevent further heat loss.
Note that many people with frostbite may be experiencing hypothermia. Saving their lives is more important than preserving a finger or foot.
Remove all constrictive jewelry and clothes because they may further block blood flow.
Give the person warm, nonalcoholic, noncaffeinated fluids to drink.
Apply a dry, sterile bandage, place cotton between any involved fingers or toes (to prevent rubbing), and take the person to a medical facility as soon as possible.
Never rewarm an affected area if there is any chance it may freeze again. This thaw-refreeze cycle is very harmful and leads to disastrous results.
Also, avoid a gradual thaw either in the field or in the transport vehicle. The most effective method is to rewarm the area quickly. Therefore, keep the injured part away from sources of heat until you arrive at a treatment facility where proper rewarming can take place.
Do not rub the frozen area with snow (or anything else, for that matter). The friction created by this technique will only cause further tissue damage.
Above all, keep in mind that the final amount of tissue destruction is proportional to the time it remains frozen, not to the absolute temperature to which it was exposed. Therefore, rapid transport to a hospital is very important.