In Paint Tool sai, I often use either one of these brushes ( Whichever one you want to use is up to you, some prefer one better over the other. I also sometimes adjust the density a little lower depending on my mood): fav.me/d5s8wpu & fav.me/d66dbke
Well whatever is necessary for you to be happy is good enough (: I havent seen it done that way before, which is why I said it's interesting XD My process is just starting from dark to light and layering the color that way.
u have no idea how grateful i am to you for these awesome hair tuts. i was simply too stubborn before trying to use photoshop instead. its full of tuts that tell how to color it but results never look even close to author's. now i practiced this night in sai what i understood from your tuts and omg i cant believe i produced these meshes they look graceful and alive and fantasy-ish just how i wanted i prolly have to work on picking the colors but thats just trial and error after all i am SOOOOO happy! here's the link [link] and im so sad i cannot provide a link to my fails in photoshop u would then understand what huge differene these made for me