- Strong outlines
- Light or minimal shading
- Dull, messy hair
Here are some examples:
The artist got all of the facial features in the right places, and the lips have a very good shape to them. But there are really only two shades here: white and light grey. That's why the face appears flat. Also notice the line around the jaw, mouth and nose.
I don't want to seem like I'm picking on anyone, so here is a drawing I did back in 2002. Although my little brother is instantly recognizable, the drawing still looks flat. Again you can see a dark outline around the jaw, the shading is very light, and the hair is just a mess. I think I put more effort into my super girly high school signature than I did on the hair.
This portrait is a little different because the artist was able to get some dark greys and blacks into his drawing - but there's very few values in between. The face is basically white and black with a little light grey shading. Because there's no shading to render the forms, the artist had to draw lines around the forehead, nose and ear.
Now let's look at some really outstanding portraits, to compare:
The reason this looks so photographic is because the artist used a full range of values: black, dark grey, medium grey, light grey, white, and everything in between. That's what makes the glasses look shiny. The artist also used an eraser to define the edge of the face instead of drawing a dark line around it.
Do you see a line around the edge of the face? Nope! It's not needed because the skin is much darker than the background, so the edge stands out even without an outline.
Can you believe this is done with pencils? Now that is how you draw hair. It looks soft because the lines are all flowing in the same directions instead of being sketched haphazardly. The strong highlights and shadows are what make it look shiny.
I'm not trying to make anyone feel bad by pointing out these typical flaws in beginner drawings. I have to continually push myself to use value instead of outlines to define forms in a face, and I hardly consider myself to have mastered it. Hopefully you've learned a little about the kind of thought that goes into a portrait!