I used Painter and the oil brushes set to blend on low pen pressure and cover on high pen pressure. Though I do the preliminary layout on pastels/ charcoal because the oils lag so much if the brushes are big. I did an extra step where I printed out my started painting in low opacity in black and white and refined the drawing on top of that and returned to painting. I find any extra time spend on getting the drawing right pays out, I just often get impatient to start painting. Glad you like it ^^.
Thanks! I don't really relish the thought of doing really detailed environments though, I must have some kind of ocd on that detail because it drives me nuts and I can't stop redoing it over and over and over! These stones must have gone through at least 4 different passes, before I managed to lock down the design.