Wallis Belgium Mist paper. Well, why not?!
(Progressive steps in slide show below)
I remember Kitty does a preliminary light charcoal sketch (with vine charcoal). She said "I try not to get too invested in the sketch, it is just for general placement". After the sketch the idea is to put in some values/colors with the liquid pigment (again, without worrying over it, because in Kitty's words: "It's all changeable and fixable"). After the paper is dry to the touch, dry pastel goes over the top of the foundation of the sketch and liquid pigment. Working in pastel is wonderful practice for considering...value...value...value!
(Kitty Wallis gives workshops, see her sidebar on her blog).
Pastel: Celeste Bergin, Pastel study, Pastel on 9x12 Wallis Paper