Nothing compares to sculpting a face on paper – or canvas – with paint. I mostly use gouache. It's water solulable and can provide a sort of water color-quality when used with a wetter brush. With a completely dry brush however, it's completely opaque. I usually start out by sketching with pencil and then prime the surface with gesso with a painting knife. Often times I mix the gesso with some colored India ink.
Most paintings start with a sketch and to make the process easier I've started to turn to my iPad where I draw using the Procreate app. I then print the sketch and use to make a pencil drawing.
Back to basics. When sketching in my pocket sized Moleskine-, Talens Art Creation- or Leuchtturm1917 sketchpad I do so in ballpoint pen. I especially love my Ohto Horizon needle point pen. A mistake while drawing in ballpoint requires problem solving and is something I welcome.