This is a character design and portrait I made straight away in ZBrush. In this case I didn't use a previous design as I wanted to practice creation and improvisation while sculpting in 3D. The main idea was a civilized-looking, sober alien character that wasn't aggressive, but did have a few hostile elements.
Preparing the Basic Model
There are many ways to start a bust or a character. I don't have any preference, but in case I started it from a standard head in ZBrush because it had all the shape I would need. Then I set the DynaMesh to quite a low poly starting point and smoothed the whole surface to get rid of the human elements of the face. After this was done, I ran DynaMesh to equalize the surface a bit more (Fig.01 - 04).
From the previous step I started to sculpt normally and kept using DynaMesh to maintain the optimal topology (Fig.05 - 06).
These are the combination of brushes I used in order to achieve something that looked like flesh or just random wrinkles for the sculpting. It can be useful to try out something like this on a sphere, as shown in Fig.07. Step 2 of the image shows the result of applying a Rake brush with a low intensity for subtle variations on the surface. Changing the size worked fine for breaking up the surface and for overlapping volumes. For the third sphere I used the Rake and Dam_Standard brushes to increase some volumes, make deeper folds and create the overall effect of flesh.