1 - The Initial line drawing
The nose is formed by a series of curved planes. This makes it difficult to draw as there are very few lines to help us describe its shape.
Start by drawing what you can see, namely the inside and outside edges of the nostrils. Then try to outline the main areas of tone that define the planes of the nose.
Draw these lightly as you want them to disappear under your shading at a later stage in the drawing.