Summarize:

If you have any of the early signs of frostbite, go inside and start getting warm. Take off wet clothes and change into dry ones or use a warm blanket to warm up. Have a warm drink like tea, hot chocolate or just warm water to start bringing your body temperature back up. The affected area will be susceptible to further damage if you go outside. Don't risk it just because you want to get back to skiing or hiking.  Fill a bowl or pot with warm water and completely submerge the affected area.  Do not use hot water, as it will heat the skin too quickly and damage the tissue. Soak the area for 30 to 40 minutes. The person with frostbite may not be able to sense the temperature accurately. As the tissue begins to warm, it's common to feel severe pain. Handling the tissue roughly could result in a lot of damage. Warm water should be the only warming mechanism you use to restore the body part to the correct temperature. Avoid doing the following:   Frostnip may be treatable at home without need for further assistance, but anything beyond that could cause long-term damage. If you experience these  symptoms, it’s important to get medical attention:
Get to a warm place immediately. Don't attempt to go back outside after warming up. If you can't find a warm place or are too far away from the closest heated building, seek shelter out of the wind and call for help. Immerse the affected area in warm water. Have someone not affected by frostbite test the water to make sure it's warm, but not hot. After about 30 or 40 minutes, full sensation should be regained, and the color should begin returning to normal. Don’t warm the area using other methods. Don’t rub the skin, either with your hands or with a towel. Don’t use dry heat, since the numb skin will easily burn  Call for medical assistance or see a doctor to assess the injuries. Blistering  Loss of sensation  Pale or discolored skin  Discharge from the affected area  Fever, confusion or dizziness