This tutorial gives some tips on how to draw the same male face of different ages, a boy, a teenager, an adult and an old man.
Please note that the purpose of this tutorial is not to provide clear proportions for drawing each face but general tips on how to make a face look younger or older.
For the proportions for drawing a male face see (can apply to teenager, adult and old man):
Drawing a Boy’s Face
For a younger looking face (compared to the older counterparts) draw larger and wider open eyes, a smaller nose and puffier lips.
Overall kids and younger people tend to have smoother less defined facial features.
Drawing a Teenager/Young Man’s Face
As people get older their faces tend to get longer and their facial feature become more defined.
For a older looking face (going from a boy to a teenager/young man) draw it slightly longer than the previous example. Draw a larger nose, bake the cheekbones slightly better defined and the lips slightly less puffy.
Drawing an Adult’s Face
For an older adults face you can make the facial features more defined and add some wrinkles on the forehead and around the eyes, nose and corners of the mouth.
Drawing an Old Man’s Face
For an old man’s face extend the wrinkles from the previous example and add some new ones. As a person gets older their skin also tends to hang more so you can draw the bottom of the cheeks/and chin further down.
This tutorial provided some tips for making a drawing of a person look younger or older but there is a lot more variety when it comes to drawing faces. If you need more examples you can always try and analyze photos of real people and see how facial structure and features tend to change with age.