It is recommended to not use any substrate at all. Some people have used paper towels but I don't use anything at all. Veilds are known to eat things and if they ingest the substrate it can cause impaction and death. If you have live plants, you can use organic soil and washed sand. Don't use the kind with fertilizer added. Then put stones on top of the soil to ensure the chameleon does not eat it. Hope this helps
Thanks bub I was told that coir is good for keeping moisture in as I'm not home all day its apparently made from coco but and doesn't have any chemicals added