The fifth part to "How to Sculpt a Face" deals with the nostrils.
STEP 17: Using the spoon shaped tool, go around the edges of the clay you just added to the cheeks and carefully blend it. You use the rounded end of the tool and GENTLY drag the added polymer clay into the face. You only want to move the edges of the added clay down to meet the face. If you push too hard you will create a recess in the face. Work at it slowly, working in small motions.
After you've worked the polymer clay with your tool, do the final smoothing with a finger, just caressing the clay to smooth it, not pushing it, (it helps if you cut your nails short like I do, then you can blend with the tip of your finger giving you more control. More control is always best when you're still learning how to sculpt a face).
STEP 18: Sometimes I leave this step until after I have finished the mouth, but in this instance I'm doing it this way. Using the rubber-tipped tool, I have carefully pushed in the beginning of a nostril.
Lean the head in a way that you can see under the nose easily. This will allow you to position the nostril easier. Make sure you compare to a photo referene to get the positioning right. It may look simple but a lot of doll makers struggle when trying to sculpt the nostrils correctly on their dolls.
STEP 19: Create little tear-drop shapes for the nostrils with the pointed ends of the holes slightly pointing to the tip of the nose. Note that the outer nostrils are quite thin compared to the part dividing the two nostrils. A lot of people tend to make the nostrils too small and close together, and ultimately it tends to make it look like a piggy snout. Keep referring to your photo reference.
Once you are happy with the size of the nostril holes, carefully tuck the outer nostril around the base of the nose. This will give the nostril some definition. The nose is quite a difficult thing to sculpt, so it would be good to practice on a scrap piece of clay a few times before committing to the doll you're working on.
STEP 20: Try to get the nose to look as symmetrical as you can, but don't waste too much time on it right now. You can keep working on it before you bake the doll. When I teach how to sculpt a face; one of the things I stress the most is that you shouldn't spend too long on a particular facial feature. When you spend too long on something, your eyes tend to glaze over and you stop seeing your mistakes. This can potentially set you back quite a bit. Work on something, then once it's reasonable, work on the next area and come back to it later with a fresh eye.
Now you need to make way for the mouth. Using your spoon shaped tool, create a hollow right around the mouth area, but be careful not to make it wider than you want your dolls mouth to be.