For the first time I'm using only Crayons and Palette Knife as ScottF suggested: "Try using crayon on a portrait some time. It´s smoother than the chalk and blends almost like oils". Seems much harder then Chalk but yes, blends almost like oils.
Because I'm not spending more then 15 min a day on this one, it will be a while until is ready. In the meantime hope you will enjoy the WIP.