I used a size 8 round brush, opacity 255, color 100%, spacing 40%, scattering 300%, blend varies...starting at 16%-100% to finish draw. Just move the pen/mouse around like crazy, moving the shapes you're creating over the canvas in any way you like. You should have some result that is similar to this. I'd love to see you awesome portrait artists create a portrait using this technique. I think that would be awesome. Above all, Have fun!
drawn in 4 min
drawn in 6 min
drawn in 9 min