Although I'm not a realism artist, utilizing techniques employed by realists help give surrealism, expressionism, and whimsical pieces a believable ambiance. One of the realism techniques I like to use is dramatic neck shadowing. It's not always the right choice, but I've been using it more often than not as of late. A dark neck shadow makes a jaw and chin seem to come forward much more than a neck of similar tone to the face. If you're an experienced artist, this may seem elementary, but if you are looking to give your characters' faces more dimension, consider working the areas around the face and not just the face itself.
In the first photo above you'll notice there is now shadow under Ivy's chin. The wood I'm drawing on can simulate skin tone. You see she looks a little flat. In the photo below her neck has been darkly shaded and I've also enhanced her cheekbones. Her face now seems to come forward more than it did in the first photo.
Tip: Don't be afraid to go dark with your shadows. The darker they are, the lighter your highlights will appear. Notice the shadow under Ivy's lip and Penguin's nose. It makes the white in her lips and his nose seem brighter. As always, have fun with it!
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