Humidity
Humidity, as might be expected for an animal that inhabits arid landscapes, is not really of paramount importance - however it is not something that should be ignored. Desert animals may get the majority of their moisture from morning dew or mist, and this type of moisture is something that is frequently overlooked in captivity.
Of course, as a bare minimum a water bowl must be provided - preferably large enough for the snake to fully immerse itself should it want to, although I have never seen a Diadem snake do this. Water should be changed daily, and whenever it is dirtied.
Something else I do for all my snakes is attempt to train them to get used to accepting water from a plastic squeeze bottle with a nozzle. These are cheaply available for about £1. Once filled with water, you carefully reach in and deposit a trickle of water on the snake’s snout. It never takes long for the snake to start sucking in this water. This is a great way of ensuring your snakes always have enough fresh water and I try to offer every snake a drink this way at least twice a week. Of course if you keep multiple snakes it is important to carefully label your bottles and keep them apart from one another to maintain hygiene! This is something I start training my snakes to do from the quarantine stage.
I also provide a small humid hide for the animals and this applies even to species found in desert and arid areas. This can be as simple as a curved piece of cork bark with damp sphagnum moss underneath it, that is periodically lifted and sprayed to keep it humid, or a plastic tub with an entrance hole cut into it that is half filled with damp coco coir and sphagnum moss.
If provided with a humid hide, bad sheds will become a thing of the past as the snake will always find enough humidity as it requires and should shed completely and in one piece every time.