Sunscreen should be applied 30 minutes before children go outside and reapplied every two to three hours when they are in the sun or water, even if the label says the product is waterproof. Stick sunscreen products with paraffin are good for those areas, since they don't drip and sting young eyes. Kids should wear photoprotective clothing and hats. Just wearing a white T-shirt isn't good enough. So wear dark colors with long sleeves and pants whenever possible.
Some companies specialize in designing photoprotective clothing.
Your dermatologist can recommend an appropriate brand.