Noses are fairly simple but still this tutorial should clear up any questions. Noses can be simple wedges or the slightly more complicated shaded version. This bit just takes alot of copying of pictures and practice.
 

	Here there is the triangle above the mouth to show the shadow cast by the nose rather then drawing the more common wedge.
	The profile view looks like this.
	This is just a triangle below where the tip of the nose is and a bit of shading to one side.
	Here is the type you will probally see the most. Notice it is just a simple wedge.