Sunburn can be very painful and uncomfortable so the first thing you need to do is cover up the affected area (if you are outside) and cool it down. Have a cool shower or place a cold compress on the affected area and drink lots of water to soothe the skin and reduce the inflammation.
Next you need to apply an after sun lotion or cream to the affected area to calm the burn and help it heal. Creams that contain Vitamin E or Aloe Vera are the most effective and be sure to re-apply a few times a day to keep the skin hydrated. Keep the affected area out of the sun for the rest of your holiday and avoid using any products containing alcohol or soap.