I'm in the middle of modeling this character, Marnie, for AnimSchool. I decided to start from the geo of our other main character, Malcolm. I figured it would be a tricky task and that's definitely been the case. This is not done yet, by far but I thought you might want to see the process.
I designed this girl as a female character for the school. I don't even have the body designed yet, but I was anxious to get started on the face.
I got past the ugly stage. I added rows to get the hard turns on the lip to keep form. I worked on the nose to get a dainty round upturned edge, like the drawing.
Wow, ugly! As I pushed the geo closer to the drawing, it strained the topology. (On the left, see the edges pulling together in places and how much cleaner and grid-like the later one on the right.) So I started rerouting the cheek, mouth, and especially forehead/brows area, connecting the rows that are more aligned so polys aren't shearing. On the right image (above) the geo flows more evenly. I removed some rows around the eyelid so I could get the right shape quicker. I can add detail back in later.
(This is being modeled in Softimage.) I started to shove things around in symmetry modeling mode, with Proportional Editing on, constantly changing falloff distance.
Wow, did he/she look ugly for a few hours!