1. Make a blank canvas in Painter, fill that canvas with layer adjuster tool and pick dark green color. I make about 3208 X 2480 pixels 300dpi. Look at the custom brush, I mainly use Oils and acrylics brush.
2. Make a messy sketch but try not to trace from reference, observes the subject until you finally got the mood, it's not 100% alike, it's normal. I use details oils with low opacity. I've done some messy sketch but this is the one that I choose.
3. Start filling that messy sketch with grey white color, I still use the same brush (detail oil brush) with low opacity around 37-50% in new layer and then as default mode 100%.
4. Start filling the hair and add some stuff like his black cloth, only for the base, it might change later as I erase his mouth that I need to re-paint by filling the failed area with lasso selection and add the same color with the background. I also use acrylics for this stage beside oils.