Portrait tutorial

I thought I'd write a kind of tutorial, or at least guide to how I draw portraits. This is just the technique I've settled into and gotten comfortable with, it might not work for everyone and the steps I'll explain here certainly don't replace good drawing fundamentals and some basic anatomy knowledge. Practice makes perfect, of course, so if my method doesn't work for you just keep trying and you'll find another method that works better for you.
So, firstly I always draw a rough curved line for the middle of the face, a horizontal line for where I think the eyes should go, and a generic outline of the head, mostly just to establish the size I want the final portrait to be. Then I almost always start by defining the real outline of the model's head and making basic marks for the positions of all the facial features, followed by adjustments wherever necessary to get the right proportions.

Once I'm more or less satisfied with the relative positions of all the features I draw them in more clearly, usually starting with the nose or the eyebrows. As I'm doing this I keep constantly aware of things I might have to adjust to keep the proportions right. The basic rule of the eyes being in the middle, nose in the middle between the eyes and chin, etc., is a good rule to start with at the very first step I talked about, but I've found that this rule doesn't always hold true. As you make progress on the drawing you'll find that another rule is more reliable, which is that almost always the outer edges of the nostrils line up vertically with the inner corners of the eyes, and the corners of the mouth with the middle of the eyes. This is the rule I keep in mind at this slightly further stage of the drawing. Next I begin to draw the basic shadows. Shadows make a face, or any shape for that matter, because I can never accurately judge the shape or proportion of something unless I've drawn in at least some rough shadows.

If I'm still satisfied with the way the shapes of the face and the proportions look after adding some basic shadow I get to work on adding more details and the more subtle shadows. This is basically all I do until I finish the drawing, just refining every detail and shadow. Throughout the process, even when the drawing is almost finished I'm still constantly adjusting things here and there to get the proportions just right. I find men a lot more challenging to draw so there was a bit more fiddling about with the proportions in this drawing than usual but it's always an ongoing process in between everything else. The smallest change in size of one feature or the tiniest shadow on another can make all the difference if you really want to capture an accurate likeness.