Apparently after modeling a bell pepper, you're qualified to model a person. Here the goal is to model a young girl. Mudbox has some basic shapes to help you get started. One is of an adult head which I'll be using. I also imported some reference images.
First thing is to get the general shape right. Here I used the grab tool a lot. Instead of pushing in and out the surface of the model like a lot of the other tools, the grab tool lets me click on a point and then pull it in any direction I want. So to lower the ear, I just clicked on the lobe and pulled downwards.
I switched the material of the model to this more matte white one. This is a tip that my other Mudbox book gave me. I allows me to see the surface more accurately as I'm working. It also means you all can see any inaccuracies as well. Along with the two reference sketches above, I was also given a bunch of photos of the real girl I'm supposed to be modeling from different angles. I put them on my phone so I could look at them easily while working. Hopefully, it won't have to explain why I have photos of a random little girl on my phone to anyone. Anyway, I used those photos to get the head shape to a more final state. Next I increased the number of polygons and created a new working layer for the nose (and one for all the future parts as well).
So I sculpted the nose followed by the mouth. On the left, you can see the top half of the head is missing. I can select different areas of the model and hide them. This is so I don't get distracted by other parts or it allows me to see what I'm working on better. It also gives my computer a break since it doesn't have to render those areas. Finally I moved onto the eye. I had some trouble smoothing out some parts of the eyelid. I forgot to mention that I have reflection turned on for all of the tools. So whatever I do on one side of the face gets mirrored on the other side.