Here's an example/ lesson page using characters from the cartoon series "Dexter's Laboratory." This lesson explains how to build a humanoid character with basic shapes, adding on to the following notes of drawing from observation. By using the simplest shapes, it's much more easy to draw your character again and again (or to be consistent with your drawings). Remember to always build larger shapes to smaller shapes, saving your details for last!
Here are various examples of different shapes that can be used in facial features: eyes, nose, mouth, ears, and hair. The possibilities are really endless, so have fun coming up with all kinds of different shapes!
Lastly, here's a tutorial on basic facial structure. Using examples from real life, you can see how there can be all kinds of different face shapes! We've also used marking lines to help with the placement of facial features so things don't get all wonky. Try looking in a mirror at your own face to do a caricature of your own face and make yourself into a character!