"How do I make my sculpts look more like Izannah Walker dolls?"
If the person is new to sculpting with Paperclay I usually encourage them to forget an Izannah resemblance in their first creation. At that point you are learning to work with the materials. My husband named one of my first Paperclay Izannah attempts Fred Merz from "I Love Lucy" back in 2006 ;-). If this is your first time handling Creative Paperclay your goal is to get a creation that looks somewhat human. If you get a likeness that seems remotely girly in your first attempt you are doing well!
If you have skills at sculpting realistic faces you will have to discipline yourself to NOT use those skills. Izannah Walker dolls are not sculpted in high relief or detail. I have shared many pictures on the Izannah Walker Chronicles of original antique Izannah dolls. They are there to use for helps in sculpting.
One of my biggest challenges for Izannah sculpting is to believe that the eyes really are about halfway between the top of the head and the chin. In my pattern there are two pre-sculpting exercises which people tend to skip, but they are important. I can usually tell if someone has done them or not. ;-). Here are those two pages: I hope this helps.
These are two pages from my "Making an Izannah Walker Inspired Doll" PDF pattern.
I wrote another post some time ago about using Picmonkey (or any photo editing program which has layers) to evaluate a sculpt in process.