However, I think I've done enough of these faceups to at least be able to give competent advice to people who have less experience than I do.
Let's start with a blank DDH-07.
Rambling: This blank head wasn't completely blank when I bought it. Someone had performed a faceup on it and then tried to wipe it clean. There were various marks on it despite that cleanup attempt. I had to clean it further in addition to using fine grit sandpaper to get rid of the obvious marks left behind by the previous owner.
After I cleaned the head to my satisfaction, I sprayed it with the non-UV cut "Flat"/Matte version of Mr. Super Clear (MSC). After the spray dried, I made some outlines with a black watercolor pencil. While black will work almost all the time, if you're going to create a blond character, brown will work as well.
Albrecht Durer / Faber-Castell watercolor pencils. You don't need to use this specific brand but I highly recommend high grade watercolor pencils to do any faceup project. If you use cheap pencils, you're going to regret it. While "professional" grade watercolor pencils tend to be a bit on the expensive side, they'll be well worth the price of admission. You're already spending hundreds of dollars on a doll body if you haven't spent the money already. There's no reason to go cheap with the watercolor pencils.
fine tip Zebra brand brush pen, extra fine tip Zebra brush pen, a black Gundam Marker, and an orange Gundam Marker to darken the eyelashes.
In terms of Gundam Markers, I used GM48 (Gundam Black, fine tip) and GM405 (Real Touch Orange 1). I used the orange marker first, and then used the black brush pens and Gundam Marker.
As for the line on the lips, I "drew" it using flat black enamel paint. I dipped a toothpick into the paint and poured the droplet onto the lips. After the paint flowed into the crevice, I wiped off the excess with a cotton swab dipped in lighter fluid.
Things you don't see well in the photos above are the pink on the cheeks. Before each new coat of MSC got sprayed, I kept using Gundam Marker Real Touch Pink 1 (GM410) and then spread out the color using the blending marker (GM400). You can finally see the cheeks being slightly pink on both sides in the photo below.
Sprayed MSC. I kept adding subtle layers of pink on the cheeks. Once I concluded I'm done adding the details to the face, I used a different MSC. I used the UV-cut version. After that dried, I used Tamiya X-22 paint on the lips.
After the X-22 dried, I gave her some eyes. I didn't intend to make her have heterochromia. I have another doll with heterochromia and because of that, I had a pair of these eyes on hand.
Hopefully, this will be useful to inexperienced faceup artists as a guide for how to perform a faceup.