I've learnt a lot from doing this portrait, precisely because things haven't gone according to plan. The fine texture that I was aiming for wasn't easy to produce using the Colorsoft pencils that I have. I find that the darker colours of this series are a bit waxy for my technique. No matter how finely I sharpen these pencils and how light a touch I use when applying the pigment, I often end up with a crayon-type finish when I particularly want a smooth or fine texture.
The solution here was to use the Colorsoft pencils for the lighter washes - again, applying the pigment with a very fine touch - and, then, swapping to Derwent Artists and, at times, Derwent Studio pencils for the darker colours. These pencils are much harder and so are less generally used for fine skin tones, but I find they suit my technique better. I rarely use even a medium pressure for skin tones and am happy to build up tones over a great many layers. Even so, I am anticipating experimenting with Prismacolor pencils, in the future. These are popular pencils for portrait artists and, although my experience with them is very limited, already I am impressed with how they handle these delicate textures - though, I must add that a combination of different types of Derwent pencils also seems to produce a pleasing result.
So, after several reworkings, I finally feel that I am on track with this portrait. I haven't quite achieved the finish I was hoping for on the face, but the rest of the head is closer to my expectations. However, this has been a very useful learning experience and I feel that it is worth continuing with it to see the end result.