Start with drawing a circle, this will represent the bulk of the head (the cranium).
Draw a cross-axis (a giant plus sign) to the center and a little lower to the center of the circle depicting the center of the face. The axis will depict which direction your face faces too.
Draw a rough face shape down the extended line depending on the face you have in mind.
Draw a line about a quarter down the original circle, that will be were the eyes are, then draw other facial features as needed.
Just keep trying until it “feels right”, there are other tutorials on the internet about it!
Draw hair with guidance of the hair line, and the top of the hair a little higher than the original circle.
Choose a light source and add shading as necessary.
And that’s about it, if you couldn’t draw a realistic face, Try again, Be patient.