You will also need a vertical center line, so put that in. Divide the lower half of the face, and put another horizontal line there, this only needs to be a little mark. This is where the bottom of the nose will be. Next, divide the lowest portion of the face again, make another horizontal mark, this is where the mouth goes. Look at the sketches on this page, and put in the rest of the details on your drawing.

Notice how the eyebrows are closer to the eyes on the men. This is because of the bone structure difference I mentioned. Men have this extra bit of bone on the forehead, the lower part of this block forms a ridge that the eyebrows rest on. I've not actually measured it, but my guess is that the distance between a man'e eyes and his eyebrows is the same as a woman's, but this distance is taken up on the bottom of this ridge, so you don't see it, making the distance appear shorter. In art terms, it's called foreshortening. as an example, hold your hand up in front of you, looking at the palm of your hand. Looks somewhat like a vertical rectangle, right? (Taller than wide) Now, lower your fingers toward you, to where you're looking mostly at your fingertips. Your hand appears to be shorter, right? Like, there's the wrist, and then the fingertips, most of your palm is unseen. Your hand is still the same length, it only appears shorter. This is what happens the the distance between a man's eyes and his eyebrows. Not all men, this is just a general principle. This is also why parting the hair on the side is a masculine thing. It makes the head look more square, and shows more of the forehead block. You can see this on the third face down. This guy doesn't have a massive jaw bone, but by showing more forehead, and sporting some facial hair, he still looks masculine. That's another structure difference between men and women: a bigger jaw.

So play around with it, make different starting shapes. Make a man's face that is wider than tall. Put just a little hair above his ears, leave the rest of his head bald, add a cigar for good measure. Make a tall thin oval for a woman's face, give her riased eyebrows, maybe a frown.