Thank you for your kind words. I use about 4 brushes for the work. If you look closely, just one brush cannot give you those depths.
Different brush for outline sketch, another one for first coating, another different one for more depth and some part of her dark hairs and another brush to block in.
Just that in this sketch, I used them simultaneously and interchangeably, so you will hardly notice unlike my previous works where I used them at various stages.