Drawing the nose or mouth can be a little bit of a task sometimes especially when it's rotated in awkward positions. In this post I hope to give my ideas on how to draw the nose and mouth. Read till the end to learn a thing or two ;-)
t is also to be noted that the wings of the nose wrap into the nostrils.

The mouth

Another very expressive feature of the face is the lips. On the face the lips wrap round various positions to give various expressions. With this stated it is important to keep in mind that the lips wrap round the mouth like a cylinder.
Drawing the lips this way would help you have a 3 dimensional idea of how it works.
Speaking of planes, the lips has few planes, not as complex as the nose. They are few but they capture the entire lips.

It is also worth noting that the lips anatomically are held by several facial muscles that stretch to form the various lip movement.

The nose

The nose is a bit difficult to render among the facial features because it pops out of the face and the appearance is therefore base on the angle by which it is being viewed.
The nose is made up of planes. And at its simplest form could be thought of as a pyramid-like shape as shown below consisting of a top plane with side planes and a bottom plane.

Under the skin of the nose lies the anatomy. The nasal bone connects with the the bridge of the nose, then the balls and wings of the nose. There is a subtle separation in the ball of the nose and this can be visible on some people.
In the minor planes things gets tricky. A lot of subtle details to bring memorised but after that you should be fluent and be able to easily recognise them.

The bottom of the nose is mostly in shadow, when shading the form, put that in mind. It also forms a cast shadow on the face.