When he gets a bad shed, put him inside a damp pillow case and leave him inside his enclosure. Usually after 30 mins all the stuck shed is inside the pillow case and not on the snake. If you want to give him a warm bath you can do it once he gets a bad shed.
What I do now that it's cold and humidity is down, I spray my snake who is about to shed with water. I spray them after their eyes turn opaque. When their eyes are clear again, they shed after a day or two so this is when I increase humidity by spraying once a day.